A 14-year-old student presents to the emergency department with a fever of 103° F for 5 days and severe sore throat. She appears toxic and complains of a generalized headache, myalgias, lethargy, and severe malaise. Her physical examination is remarkable for swollen, erythematous lips and tongue. She has cervical lymphadenopathy with 1 node measuring 2 x 3 cm. She has bilateral conjunctivitis, and her palms and soles are thickened, red, and swollen in appearance.

CBC shows a WBC of 15,000 with a mild left shift; platelets are elevated at 550,000; she is not anemic. A rapid streptococcal antigen test is negative, and a Monospot® is also negative.

Which of the following is the most likely diagnosis?
A) Cryoglobulinemia
B) Bacterial endocarditis
C) Takayasu arteritis
D) Toxic epidermal necrolysis
E) Kawasaki disease

Answer

E. Kawasaki disease

Explanation

She has all of the classic findings. She has fever, which is a requirement, and she has:

Conjunctivitis
Erythematous mouth and pharynx, strawberry tongue, and red, cracked lips
Generalized rash
Changes to the peripheral extremities, consisting of induration of the hands and feet with red palms and soles
Unilateral cervical lymph node enlarged to more than 1.5 cm in diameter
Patients must have fever and at least 4 of the 5 findings for diagnosis. If there are fewer than 4 classic findings, then a diagnosis of atypical Kawasaki’s should be considered. Treatment is with IVIG 2 g/kg x 1 time dose over 12-14 hours and aspirin in high doses initially, followed by low-maintenance doses. Usually, Kawasaki’s appears in children under the age of 5; however, cases in teenagers have been reported

You receive an emergent call on the weekend from the wife of a 32-year-old male who was just stung by several wasps and is experiencing a significant reaction. He developed facial swelling, diaphoresis, severe lightheadedness, and significant breathing difficulty. A neighbor who witnessed the event had an ephinephrine injection (EpiPen®) and administered its contents to the patient. His shortness of breath improved dramatically; his swelling reduced marginally, and his lightheadedness improved. His wife is asking for recommendations at this time.

Which of the following would be the most appropriate next step in patient care?
A) Call in a prescription for additional epinephrine with several refills.
B) Contact EMS for immediate transport to the nearest hospital.
C) An oral dose of diphenhydramine, available in the patient’s home.
D) Begin arrangements to have the patient seen by an allergist for desensitization therapy.
E) Call in a prescription for an oral steroid pulse, followed by a tapering regimen.

Answer

B. Contact EMS for immediate transport to the nearest hospital.

Explanation

An anaphylactic reaction to wasp and bee venom can be a life-threatening event and demands prompt intervention. The use of epinephrine can have a dramatic effect, but the half-life is short, and the causative venom remains in the system for a much longer period. The use of epinephrine should be viewed as a therapeutic patch to maintain the patient until transport to an appropriate facility can occur. The other options are legitimate interventions, but are of much lower importance than prompt access to emergent medical care.

Which of the following statements is true regarding immune-complex disease?
A) The rash of cutaneous necrotizing vasculitis is not an example of immune-complex disease.
B) Signs and symptoms of immune-complex disease develop from the deposition of immune complexes in the reticuloendothelial system.
C) Immune complexes do not have to persist in the circulation for the development of renal manifestations.
D) Most immune complexes are removed by the mononuclear phagocyte (reticuloendothelial) system.
Answer

D. Most immune complexes are removed by the mononuclear phagocyte (reticuloendothelial) system.

Explanation

Deposition of the immune complexes in tissues other than the reticuloendothelial system is what results in signs and symptoms of immune-complex disease. It appears that persistence of complexes is required for the development of renal disease. Immune complex-mediated vascular damage can lead to cutaneous necrotizing vasculitis.

A 27-year-old with trisomy 21 presents with weight loss, frequent diarrhea, and irritability. Abdominal distention and decreased subcutaneous fat are noted on physical exam. You suspect that he likely has celiac disease.

Because of Trisomy 21’s association with celiac disease, which of the following laboratory studies should you order?
A) Serum IgM antibody level
B) Serum IgD antibody level
C) Serum IgA antibody level
D) Serum IgG subclass levels
E) Serum IgG antibody level

Answer

C. Serum IgA antibody level

Explanation

Patients with trisomy 21 are at increased risk of celiac disease caused by injury to the mucosa of the small intestine as a result of ingestion of gluten from wheat, rye, barley, and related grains. Serologic markers include both IgA antiendomysial and IgA tissue transglutaminase antibodies. Thus, it is essential to also order a serum IgA to document that the patient is not IgA deficient. IgA deficiency is more common in celiac disease, and such patients would, therefore, have false-negative results for the serologic markers described above. A small bowel biopsy is diagnostic when the patient is still ingesting gluten and shows villous atrophy and mucosal inflammation. Approximately 1 in 250-300 people in the United States, many of whom have not been diagnosed, have celiac disease.

Which of the following statements regarding pneumonitis is true?
A) Hypersensitivity pneumonitis is cell mediated and immune complex-mediated.
B) Both allergic bronchopulmonary aspergillosis and hypersensitivity pneumonitis will respond to allergy injections.
C) Hypersensitivity pneumonitis is IgE mediated.
D) Neither allergic bronchopulmonary aspergillosis nor hypersensitivity pneumonitis will respond to corticosteroids.
E) Allergic bronchopulmonary aspergillosis (ABPA) is not IgE mediated.
Answer

A. Hypersensitivity pneumonitis is cell mediated and immune complex-mediated.

Explanation

Hypersensitivity pneumonitis is often caused by thermophilic actinomycetes. Allergic bronchopulmonary aspergillosis (ABPA) is IgE mediated and immune complex-mediated. Both ABPA and hypersensitivity pneumonitis respond to glucocorticoids. Neither, however, will improve with allergy injections. Why? Because hypersensitivity pneumonitis is not IgE mediated, and ABPA will actually worsen with allergy injections.

A woman presents to the emergency department immediately after receiving a bee sting. She has a past history of anaphylaxis and lost her EpiPen®.

She has urticaria but is not having hypotension.

Which of the following should you do next?
A) Give epinephrine 1/1,000 0.5 cc SQ.
B) Give epinephrine 0.3 mg to 0.5 mg IM.
C) Start a beta-blocker.
D) Give methylprednisolone 2 mg/kg IV.
E) Give epinephrine 1/10,000 0.5 cc SQ.

Answer

B. Give epinephrine 0.3 mg to 0.5 mg IM.

Explanation

Remember that IV steroids are not acutely effective, and trials have shown no real benefit. Subcutaneous epinephrine is no longer recommended because the absorption is haphazard; IM administration is the preferred method and provides more rapid plasma and tissue concentrations. Beta-blockade would be a disaster! It would blunt the effect of your epinephrine also! If she had bronchospasm, you would give albuterol inhalation.

You are seeing a man with Wiskott-Aldrich syndrome. He has recurrent eczema and bloody diarrhea.

Which of the following is true about this disease?
A) It cannot be treated successfully with bone marrow transplantation.
B) It is associated with low IgM.
C) He does not have increased susceptibility to infection.
D) It is associated with low IgE.
E) It is associated with low IgA.

Answer

B. It is associated with low IgM.

Explanation

Wiskott-Aldrich syndrome is an X-linked disorder characterized by eczema, thrombocytopenia, and recurrent infections. Usually these patients have high levels of IgA and IgE. They are at increased risk for infection, and they can be treated successfully with bone marrow transplantation.

You received an emergent call on the weekend from the wife of a 32-year-old male who was just stung by several wasps and is experiencing distress. She reports he has facial swelling, diaphoresis, lightheadedness, and difficulty breathing. A neighbor who witnessed the event administered an epinephrine injection (EpiPen®, Twinject®) to the patient. He was subsequently transported by ambulance to the emergency department. He received a dose of IV methylprednisolone and IV diphenhydramine, and after 10 hours, his symptoms have significantly improved. The patient is being prepared for discharge home.

In addition to a prescription for an epinephrine injection, what is the next best step in the management of this patient?
A) Referral to an allergist for immunotherapy.
B) Prednisone taper.
C) No further action is necessary.
D) Diphenhydramine for an additional 24-48 hours.
E) Albuterol MDI.

Answer

A. Referral to an allergist for immunotherapy.

Explanation

This patient has a clear history to make a diagnosis of Hymenoptera-induced anaphylaxis. The cornerstone of treatment of acute anaphylaxis is epinephrine. While commonly administered, there are no randomized controlled trials to support the use of H1 antagonists or glucocorticoids. Albuterol can be useful as an adjunctive treatment in acute anaphylaxis but will not treat underlying airway mucosal edema. Glucocorticoids are thought to help prevent the biphasic anaphylaxis, but this usually occurs within several hours after onset of the initial symptoms and would not need to be continued after discharge. Patients with anaphylaxis due to Hymenoptera should be referred to an allergist because immunotherapy for Hymenoptera can dramatically reduce the likelihood of recurrence from 30-60% to less than 5%.

A 26-year-old male with newly diagnosed Hodgkin lymphoma was admitted for workup and staging. On admit, he described severe dyspnea on exertion, and his hemoglobin was found to be 6.7 g/dL. He was typed and matched for two units of packed red cells and premedicated with acetaminophen 650 mg and diphenhydramine 50 mg. Thirty minutes into his transfusion, he develops fever to 102.5° F and shaking chills, and complains of subjective shortness of breath.

Physical exam reveals a febrile, slightly distressed male. BP 138/75, HR 110, RR 18
Pulse oximetry 98% on room air.
Chest and lung exam are normal except for tachycardia and slight tachypnea.
No skin rashes.
The nurses call you to receive directions on whether to continue the transfusion. At the first sign of fever, per protocol, they stopped the transfusion and sent for the following labs:

WBC:
3,500 cells/mm3
Hgb:
6.4 g/dL
Platelets:
182,000 cells/mm3
Direct antibody test (DAT):
Negative
Free plasma hemoglobin:
< 5 mg/dL (normal = < 5 mg/dL) Which of the following is the most appropriate next step in patient care? A) Vancomycin 1 gm IV q 12 hours and ceftazidime 500 mg q 8 hours B) Diphenhydramine 50 mg IV C) Oxygen 2 liters via nasal cannula and furosemide 40 mg IV D) Rapid infusion of Ringer's lactate and dopamine 2 mcg/kg/min E) Ibuprofen 600 mg PO and meperidine 50 mg IV

Answer

E. Ibuprofen 600 mg PO and meperidine 50 mg IV

Explanation

This patient is experiencing a febrile, non-hemolytic transfusion reaction (FNHTR). Typical symptoms include fever, chills, and subjective dyspnea without laboratory evidence of hemolysis. The hemolytic transfusion reactions are more severe and can be associated with hypotension and acute renal failure. The DAT and measurement of the free plasma hemoglobin are tests performed to assess whether acute hemolysis is occurring. This patient is hemodynamically stable and has no objective evidence of pulmonary pathology; hence, he can be managed conservatively with NSAIDs (avoid aspirin if platelet counts are low) for fever and meperidine for severe chills.

Other transfusion reactions include:

Acute hemolytic transfusion reactions
Delayed hemolytic reactions
Anaphylactic reactions
Urticarial reactions
Transfusion-related acute lung injury
You should familiarize yourself with the characteristics, diagnostics, and treatment of each type of transfusion reaction, since these are frequently tested concepts

Which of the following is not true about IgA deficiency?
A) Sinopulmonary infections may be increased in these patients.
B) IgA sprue can occur.
C) It is associated with Wiskott-Aldrich syndrome.
D) Recurrent giardiasis may be a problem.
E) The prevalence is as high as 1/300.
Answer

C. It is associated with Wiskott-Aldrich syndrome.

Explanation

All of the other statements are true. Wiskott-Aldrich syndrome is actually associated with a high IgA level, not IgA deficiency.

Which of the following tests would you order for a patient with meningococcemia?
A) Nitroblue tetrazolium assay
B) IgA level
C) Anti-thymus antibodies
D) Dihydrorhodamine flow cytometry assay
E) CH50
Answer

E. CH50

Explanation

Terminal complement deficiencies increase the risk for meningococcemia. This is screened for by checking a CH50 (or CH100), which is an easy method to see if the complement cascade is functional. Both the dihydrorhodamine flow cytometry assay and Nitroblue tetrazolium assay are used to evaluate for chronic granulomatous disease. Selective IgA deficiency is not associated with meningococcemia, therefore, checking an IgA level would not be helpful. Anti-thymus antibodies are not associated with any congenital immunodeficiencies.

A patient has a splenectomy.

Which of the following organisms is not associated with an increased risk of infection?
A) Neisseria meningitidis
B) Rotavirus
C) Haemophilus influenzae
D) Klebsiella pneumoniae
E) Streptococcus pneumoniae

Answer

B. Rotavirus

Explanation

All of the other organisms are encapsulated bacteria, which are much more difficult to eradicate in asplenic patients. Control of viruses is not generally affected by splenectomy

How does contrast dye cause an anaphylactoid reaction?
A) Because the dye induces complement activation
B) By causing an IgE-mediated reaction against the proteins in the dye media
C) By causing a direct activation of mediator release from mast cells, basophils, or both
D) By causing an IgG-mediated reaction against protein-hapten conjugates
E) By causing an IgE-mediated event against protein-hapten conjugates
Answer

C. By causing a direct activation of mediator release from mast cells, basophils, or both

Explanation

Radiocontrast media activates mast cells and basophils to release their mediators (anaphylactoid reaction). Anaphylaxis due to bee stings and foods is due to an IgE-mediated reaction against the offending protein. Anaphylaxis due to penicillin and other antibiotics is due to IgE recognition of protein-hapten conjugates.

Which of the following is not associated with severe combined immunodeficiency (SCID)?
A) A large thymus
Absent T-cell and B-cell function
B) Commonly early and severe infections—viruses, bacteria, and opportunistic
C) No tonsils or lymph nodes usually
D) Very few circulating lymphocytes (usually)
A. A large thymus

Explanation

In SCID the thymus is small or absent, so on the x-ray the thymus shadow will usually be absent. The X-linked form is the most common type. The rest of the answers are correct—remember that T- and B-cell function are both absent!

Which of the following is true about immunoglobulin A (IgA)?
A) IgA provides defense against local infections in the respiratory, gastrointestinal, and the genitourinary system.
B) All of the statements are true.
C) IgA exists as 2 subclasses.
D) IgA is the predominant immunoglobulin in body secretions.
E) IgA can prevent virus binding to epithelial cells.
Answer

B. All of the statements are true.

Explanation

IgA is found mainly at mucosal surfaces of the respiratory, gastrointestinal, and genitourinary tracts where it fights infection. It is produced in large quantities daily and mostly stays in body secretions rather than circulating in the blood. It exists as 2 subclasses: IgA1 and IgA2. Lastly, there is evidence that it can interfere with microbial binding to epithelial cell surfaces as a way to prevent infections.

A 23-year-old female comes to the clinic with complaints of vaginal irritation and swelling. She has had several episodes, which seem to be becoming more pronounced over time. She has been sexually active on four occasions with only one partner and states that she used a condom and spermicidal each time. Symptoms began within hours of intercourse and persisted for four or five days. There was minimal discharge but some labial irritation and discomfort. She was unable to use tampons during this time due to significant vaginal discomfort.

On routine examination, there is normal female genitalia without redness or discharge. Bimanual palpation is within normal limits, and DNA probes and wet mount are obtained.

Symptomatic interventions and safe sex practices are reviewed with the patient.

That evening, the patient calls reporting that the symptoms have recurred. She denies sexual activity. Contact with the lab indicates that results from the vaginal specimens are negative for evidence of STD.

The most likely diagnosis in this scenario is:
A) Chlamydia infection
B) Latex allergy
C) Conversion reaction
D) Toxic shock syndrome
E) Sensitivity to spermicidals

Answer

B. Latex allergy

Explanation

Latex allergies are becoming more common and can demonstrate a wide variability in presentation ranging from contact irritation to anaphylaxis. The patient in this scenario exhibited symptoms after contact with the latex in the condoms she used and again after contact with the latex gloves used on exam. Because she was not in contact with spermicidal at the time of the most recent outbreak, spermicidal sensitivity is much less likely. Chlamydia infections often can be asymptomatic, but the absence of laboratory data makes this less likely as well. There is no reason to suspect conversion disorder, and this diagnosis should not be entertained without at least reevaluating the patient a second time to look for evidence of evolving clinical signs. Toxic shock is associated with the use of tampons, but is generally much more severe, and does not demonstrate the waxing and waning noted in this patient’s case.

A 40-year-old man with a history of recurrent sinopulmonary infections presents for evaluation. He recovers from them fairly quickly, but he has between 4 and 6 episodes a year. Recently, he received an infusion of packed red blood cells after a major motor vehicle accident. During the infusion, he developed anaphylaxis. The blood bank and hospital checked for mismatch and found no evidence of incompatibility.

Which of the following is the likely underlying condition?
A) IgD deficiency
B) Systemic mastocytosis
C) Isolated IgA deficiency
D) Terminal complement deficiency
E) IgG deficiency

Answer

C. Isolated IgA deficiency

Explanation

Isolated IgA deficiency is the most common immunodeficiency and has an incidence between 1:600 and 1:800. People with this disorder have a normal or reduced number of B cells with surface IgA, but have an overabundance of immature cells that express both IgA and IgM. Because they do not mature normally into IgA-secreting plasma cells, there is a reduced amount of serum as well as secretory IgA. About 30-40% of people with IgA deficiency have antibodies to IgA; therefore, if they are exposed to IgA (like in blood products or IVIG), they will experience anaphylaxis. Terminal complement deficiency results in the inability to form the membrane attack complex and susceptibility to neisserial infections. Systemic mastocytosis does not lead to increased infections. IgG deficiency commonly leads to severe sinopulmonary infections. IgD deficiency does not predispose to increased infections.

Identification of specific irritants can be very helpful in constructing an interventional plan for patients with severe allergies. Several testing modalities are available to help identify potential causes of allergic response. These include skin testing with standardized reagents and radioallergosorbent (RAST) testing.

Which of the following reflects the advantage of skin testing over RAST testing?
A) Skin testing does not require trained personnel.
B) Skin testing has a lower incidence of adverse reactions.
C) Skin testing evaluates a broader range of allergic response mechanisms.
D) Antihistamines do not interfere with skin testing procedures.

Answer

C. Skin testing evaluates a broader range of allergic response mechanisms.

Explanation

Skin testing follows well-prescribed techniques, and specially trained personnel are required to administer and evaluate the testing. Although skin testing is safe, it does cause significant dermal response. Because RAST testing only requires an IV blood draw, special collection training is not required, and it is less uncomfortable for the patient. Antihistamines can limit the reaction in skin testing but do not affect RAST test results. RAST testing is limited to evaluation of IgE sensitivities, whereas skin testing evaluates a broader range of response mechanisms.

A patient with perennial allergic rhinitis is skin test positive to Alternaria.

Which of the following interventions are reasonable for avoidance of Alternaria?
A) Encasings for bedding and HEPA air filtration for the bedroom
B) Keeping windows closed
C) Encasings for the bedding and frequent laundering of linens
D) Frequent laundering of linens and HEPA air filtration

Answer

B. Keeping windows closed

Explanation

Most Alternaria arises in the outdoor environment and enters homes via doors and windows.

A 25-year-old male presents with complaints of persistent rhinorrhea. The complaints started about 3 weeks ago, shortly after he began working at a local restaurant. His work requires alternating periods in the walk-in refrigerated area and the food-preparation area. The rhinorrhea has been clear and tends to be much worse at work. He has been taking various over-the-counter medications for allergies without dramatic response.

He has no facial tenderness. The nasal mucosa is boggy with increased erythema. No purulence is noted. The oropharynx is unremarkable, and there is no lymphadenopathy. Nasal secretions are clear with no purulence. No eosinophils or neutrophils are noted on smear of nasal secretions.

Which of the following would be the most appropriate therapy for this patient?
A) Nasal alpha-agonists
B) An antibiotic course
C) Oral decongestants
D) Oral antihistamines
E) Nasal steroids

E. Nasal steroids

Explanation

Vasomotor rhinitis produces clear nasal discharge secondary to congestion of the nasal mucosa. Alternating exposure to dry and humid or to cold and warm environments can trigger this problem. Review of this scenario reveals no evidence of an infectious or allergic cause for this patient’s drainage. Oral decongestants, antibiotics and antihistamines are not primary treatments for vasomotor rhinitis. Nasal alpha-agonists run the risk of inducing rebound nasal congestion, rhinitis medicamentosa. Nasal steroids and modification of environmental exposures are the most appropriate interventions.

Which of the following does not aggravate mastocytosis?
A) Aspirin
B) Alcohol
C) Cold
D) Heat
E) Cromolyn
Answer

E. Cromolyn

Explanation

Remember that cromolyn is a mast cell stabilizer.

A 27-year-old female G2P1 presents to your office as a referral from the obstetrician for evaluation of her RPR titer. Prenatal screening, performed at her first prenatal visit at 14 weeks EGA, revealed a positive RPR test with a titer of 1:64. Her confirmatory MHA-TP is positive. HIV ELISA is negative.

Medical history is significant for only penicillin anaphylaxis at the age of 7 after receiving a penicillin injection for pharyngitis. She describes a weeklong hospital stay and emergent intubation. She does not smoke, use drugs, or drink alcohol. She has no other medical problems and takes no medicines except prenatal vitamins. This is her second pregnancy.

She states she has never had syphilis before, and she is certain this is a new infection because she was tested for syphilis during her first pregnancy 2 years prior. Review of systems is negative for paresthesias, ocular changes, changes in personality/affect or speech, lower extremity weakness, or history of stroke.

Physical examination is normal except for a slightly enlarged uterus consistent with an early second trimester gestation. Pelvic examination reveals no evidence of chancre. Skin exam is normal.

Which of the following is the most appropriate next step in patient care?
A) Arrange for penicillin desensitization and treatment with benzathine penicillin G 2.4 million units IM once per week x 3 weeks.
B) Prescribe azithromycin 2 gm orally once.
C) Hospitalize in the intensive care unit, then give benzathine penicillin G 2.4 million units IM once per week x 3 weeks.
D) Order ceftriaxone 2 gm intravenously x 1.
E) Hospitalize in the intensive care unit, then give benzathine penicillin G 2.4 million units IM once.

Answer

A. Arrange for penicillin desensitization and treatment with benzathine penicillin G 2.4 million units IM once per week x 3 weeks.

Explanation

This classic question queries whether or not you know that penicillin G is the only drug with documented efficacy in treating syphilis in pregnancy. All pregnant patients, regardless of allergy, should receive penicillin for treatment. And, if a patient is truly allergic to beta-lactams, desensitization testing should be performed, and the patient should then be treated with penicillin.

The patient in question has latent syphilis of unknown duration, as determined by her becoming positive sometime in the past two years. She has no signs or symptoms of tertiary syphilis (cardiac, gummatous, or neurosyphilis), and her duration of infection is too short to be in the tertiary stage (considering she is HIV-negative).

Dosing of benzathine penicillin G 2.4 million units IM once is utilized in cases of primary and secondary syphilis. Tripling this dosage is used in patients with late, latent syphilis (infection for > 1 year) or in patients with latent syphilis of unknown duration. This patient is considered “syphilis of unknown duration” because her last test was 2 years ago, but you do not know when in the last two years she became infected—maybe > 1 year ago or maybe only 5 months ago. Ceftriaxone and azithromycin are not approved for treatment of pregnant women with syphilis.

Allergic reactions to which of the following are not IgE mediated?
A) Contrast dye
B) Bee sting allergy
C) Penicillin allergy
D) Food allergy
E) Skin prick testing
Answer

A. Contrast dye

Explanation

Contrast dye directly causes release of mediators from the mast cells. Non-IgE mediated immediate hypersensitivity reactions are termed anaphylactoid reactions. All other answers are IgE mediated.

A 22-year-old female presents with severe urticaria, facial flushing, tongue swelling, and shortness of breath after a bee sting on his arm. Her sister had a similar reaction to contrast dye.

Which of the following correctly describes how bee stings can cause anaphylaxis?
A) By causing an IgA-mediated reaction against the proteins in the sting venom
B) Through a deficiency of C1 esterase inhibitor
C) By causing an IgE-mediated reaction against the proteins in the sting venom
D) By causing an IgE-mediated event against protein-hapten conjugants
E) By causing a direct activation of mediator release from mast cells, basophils, or both

Answer

C. By causing an IgE-mediated reaction against the proteins in the sting venom

Explanation

Anaphylaxis due to bee stings, foods, and latex is usually due to an IgE-mediated reaction against the offending protein. Anaphylaxis due to penicillin and other antibiotics is due to IgE recognition of protein-hapten conjugants. In contrast, radiocontrast media directly activates mast cells and basophils to release their mediators (anaphylactoid). Of note, anaphylactic and anaphylactoid reactions are clinically indistinguishable. The only difference is one is mediated by IgE (anaphylaxis) and the other is not (anaphylactoid).

A 30-year-old woman presents with a history of recurrent edema of the lips and face. She does not have urticaria with these episodes. She has come to the emergency department on numerous occasions thinking she has had an allergic reaction and is given epinephrine without any response. The edema gradually resolves over 1-2 days. Her brother and her father have had similar episodes but are much less affected.

What is the most likely etiology of her recurrent edema?
A) Decrease in C1 inhibitor
B) Arthus hypersensitivity reaction
C) Terminal complement deficiency
D) Atopic dermatitis
E) Hereditary IgE hypergammaglobulinemia

Answer

A. Decrease in C1 inhibitor

Explanation

She most likely has hereditary angioedema. This is an autosomal dominant disorder associated with a decrease in C1 inhibitor with a secondarily decreased C4. Recurrent nonpitting edema is the norm, and each episode may last 1-2 days. The face/lips are commonly affected. In severe cases, laryngeal obstruction and GI manifestations may occur. It does not respond to epinephrine.

A 50-year-old man was in his usual state of good health until 2 months ago when he started having problems with angioedema and laryngeal stridor. He experienced recurring episodes of swelling of his lips, tongue, and suborbital areas, which were painful but did not itch very much. He had no hives or wheezing with these episodes.

His examination shows bilateral neck mass and non-pitting edema of his face and extremities.

Laboratory shows a normal WBC with normal differential. Electrolytes are normal. C1 esterase inhibitor serum level is very low. C1q, C2, C4, and C3 levels are also quite low.

Which of the following is the most likely diagnosis?
A) Allergy to foods
B) Insect hypersensitivity
C) Lymphoma
D) Hereditary angioedema
E) Reaction to an ACE inhibitor

Answer

C. Lymphoma

Explanation

He has acquired angioedema. Syntheses of complement components in the liver and macrophages are inhibited by myelo- and lymphoproliferative diseases like lymphoma, and this results in a decrease in C1 esterase inhibitor and C1q levels. With hereditary angioedema, C1q levels are normal, and symptoms usually begin before the age of 40. Complement levels are not affected by the angioedema due to ACE inhibitors, food, or insect stings/bites.

Which of the following is true about T cells?
A) T cells lack readily detectable immunoglobulin except for IgE on their membranes.
B) T cells lack readily detectable immunoglobulin except for IgA on their membranes.
C) T cells lack readily detectable immunoglobulin except for IgD on their membranes.
D) T cells lack readily detectable immunoglobulin of any class on their membranes.
E) T cells lack readily detectable immunoglobulin except for IgM on their membranes.
Answer

D. T cells lack readily detectable immunoglobulin of any class on their membranes.

Explanation

Remember that detectable immunoglobulins are found on B cells.

A 25-year-old woman with a history of intermittent wheezing and cough after vigorous exercise presents for follow-up. She has never had an attack without it being exercise-induced. She notes that she had an attack earlier today during an aerobics class. She thinks that she developed symptoms today because she did not have enough time to warm up prior to exercise.

Which of the following treatments would most likely prevent her next attack?
A) Prednisone 30 minutes before she exercises
B) Metered-dose albuterol inhaler before she exercises
C) Theophylline therapy before she exercises
D) Inhaled beclomethasone before she exercises
Answer

B. Metered-dose albuterol inhaler before she exercises

Explanation

Exercise-induced bronchoconstriction (EIB) is defined as acute airway narrowing that occurs as a result of vigorous exercise. Inhaled short-acting beta-agonists (such as albuterol) are the single most effective agents to protect against EIB. Albuterol administered 5-20 minutes before exercise is effective for 2-4 hours in preventing EIB when used intermittently. Use of glucocorticosteroids (either oral or inhaled) prior to exercise is not effective in protecting against EIB. Daily inhaled corticosteroids (ICS) may be considered for patients with EIB who continue to have symptoms despite using inhaled albuterol before exercise, or who required daily or more frequent use of albuterol prior to exercise. Theophylline is not recommened for the treatment of EIB. Of note, warm-up exercises before planned exercise are also recommended to prevent EIB.

A recently hired 66-year-old HIV-positive male nurse is referred to your office from the occupational health clinic at the local hospital for evaluation of his vaccination status.

You are able to obtain his vaccination records from the local county health department. He received all his childhood immunizations, including 2 doses of MMR when he became a nurse in the 1980s. His last tetanus booster, Tdap, was given 4 years previously. He self-reports having had clinical varicella at the age of 7 years. The occupational health clinic is concerned that he needs the varicella vaccine because he is older than 65 and at higher risk for zoster.

Medical history includes diagnosis of HIV infection after a bout of Pneumocystis pneumonia 4 years ago, after which he has been adherent to his anti-HIV regimen. His last CD4 count was 190 cells/mm3. Currently he is without complaints.

Which of the following is the most appropriate next step in patient care?
A) Do not vaccinate him for varicella zoster.
B) Vaccinate him for MMR, Tdap, and varicella, because his original antibodies produced against varicella are likely impaired due to HIV.
C) Vaccinate him for MMR and pertussis using the new Tdap vaccine.
D) The occupational health department is correct; he should receive zoster vaccine.
E) Suggest that he quit working because he has advanced HIV infection, and he is likely to transmit opportunistic infections to patients. The need for vaccine is now irrelevant.

Answer

A. Do not vaccinate him for varicella zoster.

Explanation

The occupational health department is indeed correct he should receive the varicella vaccine; however, his CD4 count is < 200 and therefore he should not receive live-virus vaccines until his CD4 count is above 200 for a period of time. He has had varicella in the past, so he does not require varicella vaccine. He does not require Tdap again, either, until his next tetanus booster is due. There is no reason for him to quit working at this time.

A 23-year-old female returns to your clinic for a follow-up visit. She was previously seen when she developed bilateral difficulties with her pierced ears. She recently changed her ear studs and shortly afterward developed swelling and erythema to both pinnae. The ears improved with removal of all ear jewelry and 10 days of antibiotic therapy.

On today’s visit, the ears are much improved. However, the patient has developed an irritating rash involving her left wrist and lower abdomen. The wrist rash has a linear character and is so uncomfortable that the patient had to stop wearing her wristwatch. The abdominal rash is in the midline with distinct borders and is a circle approximately 1.8 cm in diameter. No other skin lesions are noted. Physical examination is otherwise normal.

Which of the following is the most likely diagnosis?
A) Köbner phenomenon
B) Drug reaction
C) Nickel sensitivity
D) Eczema
E) Psoriasis

Answer

C. Nickel sensitivity

Explanation

Linear rashes most commonly reflect an external source for the rash. The distribution of the rash in this scenario is consistent with a metal sensitivity. Nickel is a common cause and is found in many objects, including jewelry, watches, and snaps in clothing, such as in jeans. The Koebner phenomenon describes a psoriatic response to trauma, most often observed in patients with psoriasis. Exposure to drugs can cause reactions that include dermatologic findings. However, they tend to be much more diffuse. Eczema can present with localized irritation but doesn’t account for the distribution in this patient. Psoriasis would occur in other skin distributions besides the isolated metal exposed areas. All of her findings are in areas directly exposed to metal.

A 20-year-old woman presents with a history of recurrent fevers and associated sputum production. The sputum is purulent and foul smelling. She has a past medical history of recurrent upper respiratory infections. Additionally, she has had a Giardia diarrheal infection twice in the last 8 years.

Pertinent findings on her physical examination:
Coarse crackles in the left chest with decreased air movement; positive for foul-smelling sputum
She has an enlarged spleen with a span of 10 cm

Laboratory:
CBC is normal
Serum IgG is 80 mg/dL (normal 800-1,500 mg/dL)
Serum IgA is 20 mg/dL (normal 90-325 mg/dL)

Which of the following is the most appropriate treatment?
A) Corticosteroids
B) Bone marrow transplantation
C) IgA transfusion
D) Splenectomy
E) Monthly intravenous immunoglobulin

Answer

E. Monthly intravenous immunoglobulin

Explanation

This patient’s presentation is most consistent with common variable immunodeficiency (CVID). B cells can recognize antigen and multiply, but fail to differentiate to the immunoglobulin-secreting stage. Nodular lymphoid hyperplasia and splenomegaly are commonly found in these patients. Recurrent Giardia infections may also occur. These patients have low IgG, IgA, and frequently IgM. The therapy for common variable immunodeficiency is replacement of immunoglobulin—mainly immunoglobulin G—with IV or subcutaneous immunoglobulin replacement. Corticosteroids do not have a role in improving the hypogamaglobulinemia. Splenectomy has not been shown to play a role in treatment in the absence of co-morbid hematologic disease. Bone marrow transplantation also has not been shown to be helpful in CVID. Infusions of IgG, not IgA, are the mainstay of treatment.

A patient is scheduled for eye surgery in several weeks. He is currently on a nonsteroidal antiinflammatory agent.

Which of the following nonsteroidal antiinflammatory drugs irreversibly inhibits cyclooxygenase?
A) Diclofenac
B) Ibuprofen
C) Ketoprofen
D) Acetaminophen
E) Aspirin

Answer

E. Aspirin

Explanation

All NSAIDs inhibit the synthesis of prostaglandins via binding to cyclooxygenase. However, aspirin is the only agent that binds irreversibly. This is likely why aspirin is the only NSAID that inhibits platelets—platelets cannot manufacture new cyclooxygenase! Therefore, remember to stop aspirin 7-10 days before elective surgical procedures where bleeding cannot be tolerated (eye, neurosurgery, etc.).

A 26-year-old woman has had a 2-year history of rash. She describes the rash as reddish-brown spots that sometimes become raised bumps that itch, especially when she scratches them or gets hot. Additionally with these “bumps,” she has had flushing of her face, dizziness, and some abdominal pain. She has noted that her attacks can occur after she drinks beer or wine or if she takes an ibuprofen. She had an upper GI series done last week that showed an ulcer in her duodenum.

Which of the following is her most likely diagnosis?
A) Hereditary angioedema
B) Urticaria
C) Systemic mastocytosis
D) Anaphylaxis to several agents
E) Common variable immunodeficiency

Answer

C. Systemic mastocytosis

Explanation

She has a syndrome characterized by mast cell infiltration of the skin (the small bumps that are itchy—known as urticaria pigmentosa) and gastrointestinal mucosa involvement. In adults, the spleen and liver are also often involved. The ulcer she developed is from histamine-mediated hypersecretion of gastric acid. You can confirm the diagnosis by measuring urine for histamine metabolites or by measuring increased levels of serum histamine or mast cell-derived neutral protease tryptase. Common variable immunodeficiency is characterized by recurrent sinopulmonary infections, not symptoms of histamine release. Anaphylaxis to several agents might cause some of her symptoms, but would not result in persistent skin lesions or a duodenal ulcer. Hereditary angioedema manifests with repeated episodes of swelling, not with discrete urticarial lesions or persistent rash. Urticaria is not the best answer because, although the lesions of urticaria pigmentosa do have the appearance of hives when irritated, routine urticaria would not be expected to result in the other systemic symptoms described in this patient.

A 27-year-old male presents to the emergency department 20 minutes after having received a wasp sting to his right shoulder. He complains of throat tightness, shortness of breath, and generalized hives. He is alert and awake, and his blood pressure is normal.

Which of the following is the most appropriate initial treatment for this patient?
A) Albuterol 2.5 mg nebulized solution
B) Epinephrine (1:1,000) 0.3 cc IM
C) Methylprednisolone 125 mg IV
D) Diphenhydramine 50 mg IV
E) Cimetidine 200 mg IV

Answer

B. Epinephrine (1:1,000) 0.3 cc IM

Explanation

This patient is having an anaphylactic reaction based on Criterion 1 below. Note that epinephrine in the concentration of 1:1,000 is given intramuscularly to patients with an anaphylactic reaction. Because of the risk of potentially lethal arrhythmias, epinephrine should be administered intravenously (with a 1:10,000 concentration) only in profoundly hypotensive patients or patients in cardio/respiratory arrest who have failed to respond to intravenous volume replacement and several IM doses of epinephrine. Since this patient is not hypotensive, epinephrine (1:1,000) intramuscularly injected in the anterolateral thigh is the 1st line treatment. All of the other therapies listed are adjunctive therapies.

Diagnosis of anaphylaxis:
Criterion 1: Acute onset of hives, pruritis, or flushing with either respiratory compromise (dyspnea, hypoxia, wheezing) or low BP.
Criterion 2: Two of the following after exposure to a likely allergen: Skin findings, respiratory compromise, or low BP as in 1; and/or GI Sxs (abdominal pain, vomiting).
Criterion 3: Low BP after exposure to a known allergen.

A 45-year-old woman presents with complaints of episodic abdominal pain. On a few occasions, she reports that she gets swelling of her lips, tongue, and occasionally her “throat.” The most recent incident occurred while she was having a dental extraction. Many of her swelling episodes seem to occur after she has experienced some type of similar stress-induced event.

She is likely to have abnormal functioning levels of which of the following proteins?
A) C5A
B) Cyclooxygenase
C) C1 esterase inhibitor
D) IgE
E) T-cell receptor, alpha chain

Answer

C. C1 esterase inhibitor

Explanation

The classic pathway of complement activation is initiated by antibody-antigen interaction. The first complement component (C1, a complex composed of 3 proteins) binds to immune complexes with activation mediated by C1q. Active C1 then initiates the cleavage and concomitant activation of components C4 and C2. The activated C1 is destroyed by a plasma protease inhibitor known as C1 esterase inhibitor. Patients with deficiencies of C1 esterase inhibitor may develop angioedema, which can lead to death if it involves the larynx or other parts of the respiratory tract. T-cell receptor alpha chain deficiency is reported to cause increase risk of infection and autoimmune complications, not episodic swelling. Low levels of C5a, IgE, and cyclooxygenase likewise are not associated with swelling.

A 20-year-old man is bitten by a rattlesnake. He is hospitalized, and equine antivenom is administered because of incipient compartment syndrome. Twelve days later, he presents with swelling of his ankles, knees, and hands. He also develops fever. Urinalysis shows 3+ proteinuria and hematuria.

Which of the following is the most likely cause of his symptoms?
A) Late toxic effect of snake venom
B) Juvenile rheumatoid arthritis
C) Serum sickness
D) Nephrotic syndrome
E) Henoch-Schönlein purpura

C. Serum sickness

Explanation

Serum sickness, a Type III hypersensitivty reaction to the equine serum proteins in antivenom, is common. This occurs when antibody (antivenom) reacts with a target antigen (rattlesnake venom) to form circulating immune complexes. These circulating immune complexes precipitate and activate complement with subsequent small vessel inflammation and necrosis. The circulating immune complexes also can deposit in organs and glomeruli, causing arthritis and glomerulonephritis as seen in this patient.

Due to increasing symptoms occurring in individuals with latex allergies, latex-free gloves and bans on latex balloons are present in most hospitals.

Which of the following conditions has been most strongly associated with latex allergy?
A) Lumber yard exposure
B) Spina bifida
C) Eosinophilic gastroenteritis
D) Nasal polyps
E) G6PD deficiency

B. Spina bifida

Explanation

For reasons that are not clear, spina bifida has been associated with an increased risk for latex allergies. Other risk factors include being a health care worker, having a family history of allergies, and having allergies related to plants (avocado, banana, kiwi, chestnuts). Eosinophilic gastroenteritis is associated with food sensitivities but not with latex. Nasal polyps are occasionally found in individuals with aspirin allergy. Lumber yard exposure increases the risk of allergies to cedar dust and other airborne wood products, but not to latex. G6PD deficiency results in hemolytic reactions with exposures to substances that tax the G6PD metabolic pathways. Latex, however, does not result in G6PD symptoms.

You see a 28-year-old with a history of recurrent edema of the lips and face. She does not have urticaria with these episodes. She has come to the emergency department on numerous occasions, thinking she has had an allergic reaction; she is given epinephrine without any response. The edema gradually resolves over 1-2 days. Her brother and father have had similar episodes but are much less affected.

Which of the following is the most likely diagnosis?
A) Terminal complement deficiency
B) Arthus hypersensitivity reaction
C) Hereditary IgE hypergammaglobulinemia
D) Decrease in C1-inhibitor
E) Atopic dermatitis

Answer

D. Decrease in C1-inhibitor

Explanation

This is a case of hereditary angioedema, an autosomal dominant disorder associated with a decrease in C1-inhibitor with a secondarily decreased C4. Recurrent nonpitting edema is the norm, and each episode may last 1-2 days. The face and lips are commonly affected. In severe cases, laryngeal obstruction and GI manifestations may occur. It does not respond to epinephrine. Know not to use ACE inhibitors in patients with hereditary angioedema, as it can increase the risk of angioedema developing.

A 36-year-old man works as a school principal. He complains of increasingly frequent episodes of viral illnesses and sinusitis. He has 6-7 colds a year, as well as flu-like episodes that leave him feeling exhausted for several days to weeks at a time. He denies use of drugs or alcohol and states that he has had only 1 heterosexual partner for the last 5 years. He remembers that as a child he had numerous bouts of tonsillitis, strep throat, and upper respiratory infections.

Which of the following laboratory tests is most likely to help reveal his underlying problem?
A) Cold agglutinins
B) HIV test
C) Serum immunoglobulins
D) Serum protein electrophoresis

Answer

C. Serum immunoglobulins

Explanation

He most likely has immunoglobulin A deficiency. IgA serves as the first line of defense against infections of the respiratory tract, as well as infections of the GI and GU tracts. IgA deficiency is really fairly common! 1/600 individuals of European ancestry will have the deficiency. People with IgA deficiency are usually healthy, but they may have frequent episodes of upper respiratory tract infections, bronchiectasis, and chronic diarrhea. They are also more prone to allergies, asthma, and other autoimmune disorders. This patient does not have risk factors for HIV infection, and HIV infection would not account for his increased frequency of childhood infections. SPEP might help identify excess immunoglobulins, but not deficiency of them. Cold agglutinins are IgM antibodies that agglutinate red blood cells and are seen in various infections, autoimmune disorders, and lymphoma. They may also occur as a primary autoimmune disease. However, especially in the absence of symptoms suggestive of lymphoma, one would not expect them to be associated with frequent upper airway infections.

Your patient is a 26-year-old female who works as a carpenter. Over the last several years, she has experienced increasing breathing difficulties. Initially, she had a sensation of chest tightness on Mondays that would improve through the week, which she attributed to fatigue from the weekend’s activities. The tightness, however, became more persistent and now lasts through the entire workweek. She has developed a recurring dry cough and has had several courses of antibiotics, but the cough has not improved.

The patient has good air entry in all lung fields but demonstrates both mild wheezing and significant expiratory prolongation. Chest x-ray reveals hyperexpansion but no masses or infiltrates. PPD testing is negative. PFTs show findings consistent with asthma.

Which of the following would help determine if this is occupational asthma or not?
A) Perform sputum washings to detect possible eosinophils or neutrophils.
B) Perform skin testing to common allergens.
C) Perform a spirometry to determine this patient’s response to bronchodilators.
D) Give allergy shots, and if she improves, it was due to the wood dusts.

Answer

A. Perform sputum washings to detect possible eosinophils or neutrophils.

Explanation

Sputum washings demonstrating the presence of eosinophils or neutrophils is consistent with the diagnosis of occupational asthma. This may need to be performed in a specialized center. Certain professions increase the risk of airway disease arising from exposure to workplace irritants, including farmers, cotton workers, and individuals exposed to cedar dust. Bakeries are noted for the presence of multiple airway irritants such as cereal particles, molds, and egg proteins. Eosinophils and/or neutrophils are present in the sputum of most individuals with an established diagnosis of occupational asthma. Many airway complaints arise from inflammation and chronic swelling of the respiratory tract and may not demonstrate a clinically significant response to inhaled bronchodilators. Skin testing can be helpful in identifying potential offending agents, but testing a reagent is not available for all workplace substances. In addition, a positive skin test result only documents exposure and sensitization to a potential allergen, but does not prove a causative effect with airway symptoms. The diagnosis of occupational asthma is based on clinical judgment and benefits from serial airflow measurements, both at work and during periods away from the workplace.

A patient with a known T-cell defect presents for routine evaluation.

Which clinical scenario is most suggestive of a T-cell defect?
A) Recurrent and frequent infections with fungi, viruses, and protozoa
B) A history of frequent and recurrent episodes of otitis media, sinusitis, and pneumonia
C) Recurrent bacterial infections with encapsulated organisms
D) Increased incidence of autoimmune disease—especially systemic lupus erythematosus
E) Increased susceptibility to diarrhea as a result of infection with Giardia lamblia

Answer

A. Recurrent and frequent infections with fungi, viruses, and protozoa

Explanation

Failure to thrive associated with diarrhea, recurrent viral infections, infection with opportunistic organisms, and fungal infections suggest an underlying T-cell immunodeficiency. Recurrent bacterial infection with encapsulated organisms such as pneumococci and Haemophilus influenzae are frequently observed with B-cell defects, as is a history of recurrent sinopulmonary infections. Susceptibility to infection with Giardia also is observed with B-cell deficiencies. Autoimmune diseases are more frequent with complement deficiencies.

A 25-year-old male presents with recurrent episodes of abdominal pain and stress-induced edema of the lips and tongue. Occasionally with severe stress, he will also have laryngeal edema. As a child, he suffered from recurrent bouts of abdominal pain and hand swelling. As an adult, the swelling episodes have gotten progressively worse.

With which of the following proteins is he most likely to have a low functional or absolute level?
A) Bradykinin
B) Surface immunoglobulin A
C) IgE
D) C5A
E) C1 esterase inhibitor

Answer

E. C1 esterase inhibitor

Explanation

The patient most likely has hereditary angioedema (HAE). Bradykinin is the mediator responsible for angioedema in patients with HAE. Reduced levels or low functional levels of C1 esterase inhibitor leads to excessive bradykinin release and angioedema. C1 esterase inhibitor replacement protein was approved in October 2008 for treatment of acute attacks of HAE.

C5A is incorrect because it is an anaphylatoxin that can induce angioedema episodes. Low C5A levels would not be associated with angioedema. IgE is a nonspecifc marker of allergic disease. Low surface immunoglobulin A would not be associated with angioedema. Bradykinin is not correct because quite the contrary, high (not low) levels of bradykinin are present in plasma of patients with HAE.

A 17-year-old male presents with abdominal pain, nausea, and vomiting. With this episode, he has noted a rash and complains of severe arthralgias. He has never had this before.

His physical examination is significant for palpable purpura on his buttocks and lower extremities. None of the lesions are above his waist. Additionally, he has guaiac-positive stool. Laboratory is sent and is remarkable for a urinalysis that shows mild proteinuria and red blood cell casts. Other studies are normal, including his CBC.

Which of the following is the most likely diagnosis?
A) Anaphylaxis to a hapten
B) Leukemia
C) Anaphylaxis to a protein
D) Job syndrome
E) Henoch-Schönlein purpura (HSP)

Answer

E. Henoch-Schönlein purpura (HSP)

Explanation

He has the classic findings of purpura that are confined to the buttocks and lower extremities. Additionally, he has signs of gastrointestinal involvement as well as glomerulonephritis. The classic triad of Henoch-Schönlein purpura (HSP) are purpura, arthritis, and abdominal pain. HSP is a small vessel vasculitis characterized by deposition of IgA immune complexes. Most of the time HSP is self-limiting, but occasionally it can progress to a chronic form. Leukemia can present with purpura but typically has abnormalities on CBC. Job syndrome (Hyper-IgE syndrome) is characterized by recurrent infections and markedly elevated immunoglobulin E.

A 33-year-old woman presents with facial pain and nasal congestion. She reports onset of a sore throat and rhinorrhea 5 days ago. Over the past 48 hours, she has had facial pressure over the maxillary sinus and yellow nasal discharge. On exam: Temp 99.2° F, BP 110/70 mmHg. Nose: Swollen turbinates. Neck: No adenopathy. Chest: Clear.

Of the following, what would you most likely recommend?
A) Decongestants/nasal irrigation
B) Decongestants/nasal irrigation + metronidazole
C) Decongestants/nasal irrigation + amoxicillin
D) Decongestants/nasal irrigation + TMP/SMX
E) Decongestants/nasal irrigation + amoxicillin/clavulanate

Answer

A. Decongestants/nasal irrigation

Explanation

This patient presents with a 5-day history of rhinorrhea, sore throat, and facial pain. She is afebrile with swollen nasal turbinates on exam. Her symptom complex is most consistent with the common cold. The CDC campaign to limit antibiotic use advises to wait 7-10 days before considering treatment with antibiotics for “sinusitis” for facial pain/persistent congestion. The yellow discharge does not increase the likelihood of a bacterial infection. The best treatment would be to begin saline nasal irrigation and topical decongestants for several days without antibiotic treatment.

Which of the following is an example of delayed hypersensitivity (Type IV)?
A) Tuberculin sensitivity
B) Drug-induced cytopenia
C) Graves thyroiditis
D) Serum sickness
E) Peanut allergy
Answer

A. Tuberculin sensitivity

A 40-year-old man presents to you with a history of recurrent rash. He describes an urticarial rash that sometimes leaves a discoloration after the lesions have resolved. He reports intermittent arthralgias with the rash. Otherwise, his physical examination is normal. He currently has some of the lesions. His laboratory is significant for an ESR of 76 mm/hour.

Which of the following should you do next to evaluate his findings?
A) Skin biopsy
B) Patch test
C) C1 esterase inhibitor activity level
D) IgE
E) Wheal-and-flare allergy skin test battery
Answer

A. Skin biopsy

Explanation

The combination of residual skin lesions, arthralgias, and elevated ESR are not consistent with hereditary angioedema or most urticarial diseases. It is much more likely due to urticarial vasculitis, which could be confirmed by skin biopsy. Chronic urticaria is rarely allergic in nature; therefore, allergy skin testing and IgE levels are not likely to be helpful. C1 esterase inhibitor activity level would be useful in hereditary angioedema, but not in this entity. The patch test would be helpful in diagnosing contact dermatitis.

A 17-year-old female comes to your office with a 3-day history of purulent nasal discharge, sinus tenderness, and fever of 102° F.

Physical Exam:

Her nasal turbinates are erythematous and very swollen.
She has purulent nasal secretions and bilateral maxillary sinus tenderness.
Lungs are clear to auscultation.

Past Medical History:

She has had numerous episodes of acute sinusitis in the past year (2 documented with CT scans of the sinus), all requiring antibiotics to clear.
She has chronic episodes of diarrhea.
She also suffers from seasonal allergies.
No hospitalizations.
Immunizations are up to date.

You treat her for acute sinusitis and order which of the following test(s)?
A) Neutrophil nitroblue tetrazolium dye reduction test (NBT)
B) Calcium level
C) Abdominal ultrasound
D) Serum IgE levels
E) Serum IgA levels

Answer

E. Serum IgA levels

Explanation

This patient has had recurrent sinus infections, allergies, and chronic diarrhea, findings of which are associated with IgA deficiency. It is defined as extremely low (< 7 mg/dL) or absent serum IgA and secretory IgA. IgA deficiency is the most common type of primary immune deficiency, occuring in up to 1 in 300 persons. Clinical problems can be variable, ranging from no significant problems to recurrent sinopulmonary and GI illness. Treatment is antibiotic therapy as indicated and avoidance of blood and plasma products to prevent IgA sensitization. Neutrophil nitroblue tetrazolium (NBT) dye reduction test would only be helpful in diagnosing chronic granulomatous disease. An abdominal ultrasound would not be helpful in determining the cause of her chronic diarrhea. A colonoscopy may be more appropriate to evaluate for autoimmune inflammatory bowel disease such as Crohn disease and ulcerative colitis, both of which are at increased risk in patients with IgA deficiency. A low calcium level may be seen in patients with complete DiGeorge syndrome, but not in patients with IgA deficiency. Elevated serum IgE levels may be seen in atopic individuals, but is nonspecific, and would not lead to the appropriate diagnosis.

A 44-year-old male presents with multiple vesicular lesions over both arms. He had been doing yard work in an overgrown wood lot. The lesions developed about an hour after he returned home and have been weeping since their appearance. The patient has multiple vesicular lesions, primarily in linear groupings. There also is some clean yellow “weepage” from some of the larger lesions. You suspect he might have been exposed to poison ivy.

Which of the following is the best next strategy for controlling the vesicular lesions?
A) Prescribe steroids to keep weepage from becoming crusty.
B) Advise the patient to avoid people because the serous discharge can transmit this disease from person-to-person.
C) Carefully wash all clothing and tools from the work area to stop reinitiation of this rash.
D) Prescribe a leukotriene inhibitor to prevent further vesicle formation.

Answer

C. Carefully wash all clothing and tools from the work area to stop reinitiation of this rash.

Explanation

Plants from the Toxicodendron genus, including poison oak, sumac, and ivy, are capable of causing significant symptoms. The plants produce an oleoresin that is absorbed by the skin and forms haptens, which are strong immune stimulants. The skin reaction involves pruritus and vesicular eruptions. Leukotriene inhibitors have no role in blocking or treating this process. The process is not contagious, and the secretions do not contain free oleoresin. Therefore, the rash does not transmit from person-to-person by secretion contact. The resin, however, clings to tools and clothing for extended periods and can reinitiate a reaction with subsequent contact. Impetigo is a common complication of this process, and crusting of the secretions should prompt consideration for antibiotic therapy. In those situations, steroids should be used with clinical caution.

During B-cell development, which of the following is expressed the earliest?
A) Surface immunoglobulin A
B) Surface immunoglobulin G
C) Surface immunoglobulin D
D) Surface immunoglobulin M
E) Surface immunoglobulin E
Answer

D. Surface immunoglobulin M

Explanation

Remember that surface immunoglobulin M is the first immunoglobulin class produced. IgM is the default immunoglobulin. The other immunoglobulin isotypes are produced after B-cell class switching.

HLA-B27 is a common antibody in some disorders.

Which of the following is not associated with a positive HLA-B27?
A) Reactive arthritis (previously referred to as Reiter’s syndrome)
B) Psoriatic arthritis
C) Acute anterior uveitis
D) Ankylosing spondylitis
E) Rheumatoid arthritis

Answer

E. Rheumatoid arthritis

Explanation

All of the other choices are associated with the possibility of having a positive HLA-B27 antigen. It is not seen in rheumatoid arthritis.

A 17-year-old is seen for mouth breathing and chronic rhinorrhea. His symptoms do not improve with antihistamines. He denies nasal itching or eye symptoms. He has used topical nasal steroids with poor compliance, but with possibly some benefit.

Which of the following is the most likely diagnosis?
A) Foreign body
B) Idiopathic rhinitis (nonallergic rhinitis)
C) Adenoidal hypertrophy
D) Allergic rhinitis
E) Sinusitis

Answer

B. Idiopathic rhinitis (nonallergic rhinitis)

Explanation

At this age, prominent nasal congestion without itch, sneeze, or response to antihistamine is likely to be caused by idiopathic rhinitis (previously known as nonallergic or vasomotor rhinitis).

Your patient is a 36-year-old male who presents with complaints of “panic” attacks that have been increasing in frequency over the last year. He has experienced episodes of palpitations and flushing that come on unexpectedly and resolve after several hours. He has also had increasing crampy pain, primarily in the lower abdominal area, and frequent headaches. During this time, he also has developed recurrent swelling of his lower extremities with itching to the skin and the appearance of several reddish-brown maculae.

On physical exam, his vitals are normal. His cardiac exam reveals a regular rate and rhythm with no ectopy. His abdomen is soft with normal bowel sounds and no hepatosplenomegaly. He has several maculae on the lower legs with mild edema that seem to increase after initial palpation and become more pruritic.

Notable laboratory results:

Urine metanephrine:
83
24-96 mcg/24 hours
Urine vanillylmandelic acid (VMA):
6.7
2-7 mg/24 hours
5-hydroxyindoleacetic acid (5-HIAA):
20.1
0-31.4 μmol/24 hours
Tryptase:
82.4
2-23 ng/mL
C1 esterase inhibitor
(C1-INH):
18.4
16-33 mg/dL
In light of the above information, which of the following is the most likely cause of this patient’s symptoms?
A) Systemic mastocytosis
B) Carcinoid tumor
C) Angioedema
D) Pheochromocytoma

Answer

A. Systemic mastocytosis

Explanation

All of the above processes can present with flushing, palpitations, and edema. The lab values, however, are most consistent with systemic mastocytosis. In addition, the reddish-brown skin lesions represent urticaria pigmentosa, cutaneous clusters of mast cells. They are noted to cause urticaria and flushing when palpated, a reaction referred to as a Darier sign. A negative urine metanephrine and VMA test make pheochromocytoma unlikely, and a normal 5-HIAA test likewise reduces the likelihood of a carcinoid tumor. A normal C1-INH also makes angioedema unlikely. Tryptase is a protease found in mast cells, and elevated levels are found in anaphylactic reactions and conditions with increased mast cells, including mastocytosis.

Which of the following is true with regards to DiGeorge syndrome?
A) Cardiac abnormalities never occur.
B) It is not associated with hypoparathyroidism.
C) Immune deficits in most with DiGeorge syndrome are minimal except for those with “complete DiGeorge’s.”
D) Thymic abnormalities do not occur.
E) Facial abnormalities do not occur.
Answer

C. Immune deficits in most with DiGeorge syndrome are minimal except for those with “complete DiGeorge’s.”

Explanation

Most cases of DiGeorge are not “complete,” and therefore there still is adequate immune function, and most patients do not have issues with infections. Facial, parathyroid, thymic, cardiac, neurologic, and renal problems are all possible. Each affected area varies independent of the others.

In complete DiGeorge syndrome, immune function is absent as in SCID, and these patients have the same risks from blood and vaccines. Most with “complete” also have profound hypoparathyroidism. Therapies for those with the severe, complete form include IVIG, isolation, antibiotics as needed, Ca++ management, and cardiac management. Bone marrow transplant is not very helpful (no thymus for production of new T cells). Thymus transplantation is promising.

A 45-year-old woman with an abdominal mass palpable in her right upper quadrant is seen for evaluation. You order an abdominal-computed tomography exam. While at the radiology suite, she receives her intravenous contrast. Within minutes of the injection, she develops widespread urticaria, facial flushing, and her tongue starts to swell. She also becomes hoarse and says that her “throat is swelling up.” She develops stridor and requires emergency intubation with mechanical ventilation.

Which of the following has caused her acute event?
Contrast dye transformation into formaldehyde
A) An IgE-mediated event against native proteins
B) A deficiency of C1 esterase inhibitor
C) An IgE-mediated event against haptens
D) Direct activation of mediator release from mast cells, basophils, or both

Answer

E. Direct activation of mediator release from mast cells, basophils, or both

Explanation

The patient is having anaphylaxis to radiocontrast media. Anaphylaxis typically occurs through an IgE-mediated mechanism, most commonly triggered by bee stings, foods, and latex. Radiocontrast media, however, can trigger anaphylaxis through an IgE-independent mechanism, directly activating mast cells and basophils to release the mediators of anaphylaxis. Traditionally, this type of reaction has been referred to as anaphylactoid reactions. Anaphylaxis due to penicillin and other antibiotics is due to IgE recognition of protein-hapten conjugates. Finally, dialysis can induce anaphylaxis with complement activation.

A 37-year-old man presents with a history of recurrent sinopulmonary infections. He recovers from them fairly quickly, but he has between 5 and 7 episodes a year. Recently he received an infusion of packed red blood cells after a major motor vehicle accident. During the infusion he developed anaphylaxis. The blood bank and hospital checked for mismatch and found no evidence of incompatibility.

What is his likely underlying condition?
A) Terminal complement deficiency
B) IgG deficiency
C) Systemic mastocytosis
D) IgD deficiency
E) Isolated IgA deficiency

Answer

E. Isolated IgA deficiency

Explanation

Isolated IgA deficiency is the most common immunodeficiency and has an incidence between 1:600 and 1:800. People with this disorder have a normal or reduced number of B cells with surface IgA, but have an overabundance of immature cells that express both IgA and IgM. The problem is that it appears the cells cannot secrete IgA effectively. Thus, there is a reduced amount of serum as well as secretory IgA. About 30-40% of people with IgA deficiency have antibodies to IgA; thus, if they are exposed to IgA (like in blood products or IVIG), they will have anaphylaxis.

A 26-year-old patient has complaints of eczema that has been recurrent since childhood but has worsened. The patient has used multiple interventions in the past with variable success.

Which of the following is the most appropriate pharmacotherapy?
A) Prescribe H 2 blockers to reduce the pruritus associated with eczema.
B) Advise patient to use soapy water to reduce skin irritants that cause eczema.
C) Prescribe high-dose steroid cream to be applied where needed.
D) Prescribe low-dose oral steroids to suppress long-term eczematous symptoms.
E) Prescribe tacrolimus cream (Protopic®) to be applied on the eczema.

Answer

E. Prescribe tacrolimus cream (Protopic®) to be applied on the eczema.

Explanation

Eczema is a recurrent inflammatory condition of the skin that typically begins in childhood and often persists into adulthood. Most treatments focus on control of the long-term symptoms and avoidance of exacerbating factors. Topical steroids are a useful adjunct in eczema therapy. Oral steroids, however, increase the potential of systemic side effects and do not improve the long-term course for eczematous patients. Strong topical steroids also have serious side effects. Immune modulators such as tacrolimus and pimecrolimus are approved for eczema treatment and do not affect the adrenocortical axis. Pruritus is a significant component of eczema and controlling the itch tends to improve the rash. Antihistamines can be very helpful, but H 2 blockers are not generally effective in this role. Patients with eczema display an increased incidence of skin infections, particularly with S. aureus . Frequent soapy water increases the loss of vital skin emollients and tends to worsen the symptoms of eczema.

A 45-year-old woman presents to the emergency department immediately after being stung by a bee. She has a past history of anaphylaxis and had lost her self-injectable adrenaline. She has diffuse urticaria and abdominal pain. Her blood pressure is normal.

Which of the following is indicated?
A) Give epinephrine 1/10,000 0.5 cc SQ.
B) Start beta-blocker.
C) Give IV methylprednisolone sodium succinate (Solu-Medrol®) 2 mg/kg IV.
D) Give epinephrine 1/1,000 0.5 cc IV.
E) Give epinephrine 1/1,000 0.5 cc IM

Answer

E. Give epinephrine 1/1,000 0.5 cc IM.

Explanation

Expect at least one of these questions on an exam. The treatment of choice for anaphylaxis is epinephrine 1/1,000 0.5 cc intramuscularly in the anterolateral thigh. Remember that IV steroids are not effective acutely. It takes 4-6 hours for steroids to have any effect. She is not hypotensive, so she does not need epinephrine IV. If she was hypotensive, you could use the 1/10,000 IV formulation of 5 cc along with fluid expanders. Beta-blockade would be a disaster, and you would not want to do that! It will blunt the effect of your epinephrine. If she had bronchospasm, you can consider nebulized albuterol. Use of diphenhydramine and cimetidine is also helpful after the epinephrine. But epinephrine is always first-line!

A 40-year-old man with aplastic anemia is administered a treatment. Ten days after beginning therapy with this agent, he develops clinical disease that presents with fever, malaise, arthritis, and nausea. Soon after, he develops an urticarial rash. He worsens and develops melena and lymphadenopathy. Laboratory is significant for a markedly diminished C3, C4, and CH50. He has high levels of circulating immune complexes.

This is likely due to which of the following therapeutic agents?
A) IVIG
B) Corticosteroids
C) Equine antithymocyte globulin
D) Gold therapy
E) Alkylating agent and corticosteroid

Answer

C. Equine antithymocyte globulin

Explanation

The patient has developed serum sickness from equine antithymocyte globulin. All of his features are classic for a severe reaction to an agent like this one. Usually, it occurs 1-3 weeks after receiving the therapy. An exam is also likely to ask this question in reference to a snake bite in a patient who receives antivenom. Serum sickness is a hypersensitivity reaction that occurs when an antibody reacts with a target antigen to form immune complexes. The immune complexes precipitate in small blood vessels and activate complement with subsequent small vessel inflammation and necrosis. Serum sickness is usually self-limited after withdrawal of the offending drug and the antigen is cleared. Occasionally, corticosteroids are given. Of the available choices, equine entithymocyte globulin is the most likely cause of serum sickness.

You are asked to evaluate a 27-year-old male who has been experiencing rhinorrhea and nasal congestion daily for the preceding 2 months. He is employed as a landscape assistant and works primarily outdoors. He has been using over-the-counter nasal decongestants that work well for him, but he is requiring increasing usage to control symptoms.

On examination, the patient has markedly edematous nasal mucosa. There is no purulence to the discharge, which is primarily clear in nature. There is no facial tenderness. Nasal smear is negative for leukocytes and eosinophils.

Of the following, the most likely diagnosis in this patient is:
A) Chronic sinusitis
B) Vasomotor rhinitis
C) Rhinitis medicamentosa
D) Allergic rhinitis

Answer

C. Rhinitis medicamentosa

Explanation

Rhinitis medicamentosa arises in patients using inhaled nasal adrenergic agents. These agents cause vasoconstriction, which can reduce nasal congestion, but they also can lead to a rebound phenomenon. Repetitive usage leads to a persistent nasal congestion. Vasomotor rhinitis is common in individuals who experience dramatic or frequent changes in temperature or humidity, as often occurs in outdoor workers. Persistent nasal edema is not expected with simple vasomotor rhinitis. Allergic rhinitis and chronic sinusitis are commonly associated with eosinophils and neutrophils, respectively, in the nasal smears.

A 23-year-old graduate student with a negative past medical history, except for gonorrhea at the age of 18, presents for evaluation. He says that he began having problems when he started working in the basic science research laboratory of his school. He says that since working there he has had episodes of shortness of breath, stuffy nose, cough, fever, and chills. He feels bad most of the day. He feels better by Sunday evening, but on Monday his symptoms return. He works with mice in a laboratory at the school from Monday through Friday. He says that he has been well the past few days (today is Monday). He doesn’t smoke and occasionally drinks a beer on the weekend. On physical examination, you find nothing—everything is normal. However, a chest radiograph is done and shows ill-defined patchy infiltrates. His laboratory studies, including CBC, lytes, BUN, and creatinine, are all normal. His ESR is slightly elevated at 28. Pulmonary function studies are done and show reduced lung volumes.

Which of the following is the most likely diagnosis?
A) Acute bronchitis
B) Acute hypersensitivity pneumonitis
C) Leptospirosis
D) Asthma
E) Granulomatosis with polyangiitis (formerly Wegener’s

Answer

B. Acute hypersensitivity pneumonitis

Explanation

Given the temporal relationship between the exposure to the mice, the nonspecific infiltrates, and the restrictive pulmonary physiology, acute hypersensitivity pneumonitis is the most likely diagnosis. Acute hypersensitivity pneumonitis is characterized by an influenza-like illness and respiratory symptoms after exposure to the offending antigen. In this case, the antigen is from proteins found in mice urine, serum, and/or pelt. The best therapy is to remove the patient from the environment, because chronic exposure could lead to a subacute or chronic form of this disease with potentially serious physiologic consequences. The clue to the diagnosis is that the symptoms improve when the patient is away from work.

Granulomatosis with polyangiitis (formerly Wegener’s) is characterized by the clinical triad of upper airway involvement, lower respiratory tract involvement, and glomerulonephritis. Both acute bronchitis and leptospirosis can result in influenza-like symptoms. However, a history of symptoms improving when the patient is away from work argues against granulomatosis, acute bronchitis, and leptospirosis. Although there is a casual relationship between workplace exposure and occupational asthma, one would not expect to find pulmonary infiltrates with asthma. Furthermore, the presence of influenza-like symptoms (stuffy nose, cough, fever, and chills) and restrictive lung pathology argues against occupational asthma.

A 42-year-old woman with no prior medical history presents as a new patient. Her eldest sister has a history of anaphylaxis to contrast dye, and her other older sister has a history of anaphylaxis to bee stings. She comes in today with a sore throat. You are able to confirm Streptococcus pyogenes, and you start her on the appropriate oral antibiotic for this infection. She returns that afternoon to the emergency department with a complaint of urticaria, facial flushing, and her tongue starts to swell. She responds to therapy and is observed in the emergency department.

Which of the following is the mechanism for her anaphylaxis?
A) She has a deficiency of C1 esterase inhibitor.
B) She had IgE recognition of protein-hapten conjugates.
C) She had direct activation of mediator release from mast cells, basophils, or both.
D) She had IgE recognition of native proteins.
E) She somehow got exposed to contrast material while in your office.

B. She had IgE recognition of protein-hapten conjugates.

Explanation

Anaphylaxis due to penicillin and other antibiotics is due to IgE recognition of protein-hapten conjugates. Anaphylaxis due to bee stings, foods, and heterologous serum (such as tetanus antitoxin) is likely due to an IgE-mediated reaction against the offending protein. In contrast, radiocontrast media directly activates these cells to release the mediators of anaphylaxis. Finally, dialysis induces anaphylaxis with complement activation.

A healthy 26-year-old woman presents to your office complaining of “welts.” She states that she exercises 4x/week, and, after she begins her exercise, her skin “breaks out in welts and itches.” She is able to tolerate the rash and completes her exercise regimen, but she has intense skin itching for 30 minutes after exercise. Hot showers make the itching and welts worse. These irritating rashes after exercise have been occurring for 3 years now. She takes only multivitamins and has no medical history. She does not smoke or use drugs. She drinks alcohol occasionally. Review of systems is negative for nausea, vomiting, diarrhea, fevers, chills, night sweats, and weight loss.

Physical exam is normal.

Which of the following is the most appropriate next step in her care?
A) Prescription of diphenhydramine before exercise
B) Measurement of complement levels
C) Reassurance and suggest she take cool showers after exercise
D) Measurement of erythrocyte sedimentation rate (ESR) and/or C-reactive protein (CRP)
E) Complete blood count with differential

C. Reassurance and suggest she take cool showers after exercise

Explanation

This patient suffers from hives induced by exercise and hot water, otherwise termed “cholinergic urticaria.” Because the classic features of cholinergic urticaria can be ascertained from her history (occurs after exercise, associated with sweating or hot water), further workup need not be done. Urticaria is divided into “acute” and “chronic” (occurs almost daily and lasts > 6 weeks). Acute urticaria can be due to several etiologies including medications, insect stings, latex allergy, food allergies, parasitic infections, contact allergens, ingested allergens (such as radiocontrast medium), and reactions to certain physical conditions such as cold (“cold urticaria”) and heat (“cholinergic urticaria”). Chronic urticaria is more aggravating and worrisome and can be caused by systemic diseases such as autoimmune states (lupus or thyroid dysfunction) and diseases of basophils and thrombin formation. Complete blood counts, sedimentation rates, and complement levels are tests to distinguish the etiology of urticaria in patients without an obvious cause. Cholinergic urticaria is frequently resistant to treatment with antihistamines, although these drugs are the mainstay of treatment for cold urticaria.

Which of the following is not an example of immediate hypersensitivity?
A) Peanut allergy
B) Reaction to Td immunization
C) Bee sting anaphylaxis
D) Allergic rhinitis
E) Latex allergy
Answer

B. Reaction to Td immunization

Explanation

This is an example of an Arthus Type III reaction. It occurs maximally at 8-24 hours and causes hemorrhagic indurated lesions.

A 41-year-old man is stung by a be while working in Greece and Turkey. He quickly develops anaphylaxis and requires intubation and aggressive cardiorespiratory support. He recovers well and returns to work the next week.

Which of the following are true about anaphylactic reactions?
A) Absence of skin findings (urticaria, etc.) rules out anaphylaxis.
B) Anaphylaxis always begins within 5-10 minutes after antigen exposure.
C) Anaphylaxis is IgE mediated.
D) Radiocontrast dye more commonly causes anaphylaxis and not anaphylactoid reactions.
E) Anaphylactoid reactions are IgE mediated.

Answer

C. Anaphylaxis is IgE mediated.

Explanation

Anaphylaxis is an IgE-mediated systemic reaction to an allergen (hypersensitivity reaction, Type I). A similar reaction that is not IgE mediated is known as “anaphylactoid.” Anaphylaxis is more common in adults than in children. Anaphylactoid reactions are most commonly due to aspirin, NSAIDs, and radiographic contrast. Anaphylaxis is a result of a huge activation of IgE-sensitized mast cells by the allergen. Histamine release occurs within 5-10 minutes after exposure to the allergen, and histamine remains at high serum levels for at least an hour. Histamine interacts with specific receptors and causes increased heart rate, vascular permeability, vasodilatation, smooth muscle contraction, sensory nerve irritation, and coronary artery vasospasm. Multiple other mediators are released; some, such as leukotrienes and prostaglandins, may also have vascular effects. The complement pathway also may be activated. The cumulative effect of all of these mediators is vasodilatation, hypotension, and loss of intravascular fluid volume. This can then be followed by vasoconstriction and myocardial depression with severe hypotension.

Anaphylaxis may begin within 5 to 30 minutes after antigen exposure or can be delayed up to 2 hours. Urticaria and angioedema are the most common manifestations of anaphylaxis, followed by flushing and respiratory tract symptoms in about 50% of those affected. Absence of skin findings does not rule out anaphylaxis. The effects of respiratory tract edema are the most life-threatening. Cardiac arrest can occur without any of the other symptoms. GI complaints occur in about 1/3 of patients.

A 20-year-old woman presents with recurrent sinopulmonary infections and has developed severe respiratory insufficiency. CXR shows a right upper lobe infiltrate with central and distal bronchiectasis. She has depressed levels of IgA, IgE, and IgG2 subclass on laboratory testing. Additionally, she is noted to have anergy to cutaneous testing. She has had progressive loss of muscle coordination since she was 2 years old, and from the age of 10, she has been confined to a wheelchair.

Which of the following is her likely diagnosis?
A) An abnormality on chromosome 12
B) Severe combined immunodeficiency
C) Friedreich ataxia
D) Cystic fibrosis
E) Ataxia-telangiectasia

Answer

E. Ataxia-telangiectasia

Explanation

Ataxia-telangiectasia (AT) is a rare autosomal recessive disorder characterized by neurodegeneration, immunodeficiency, extreme sensitivity to radiation, and predisposition to cancer. The progressive cerebellar ataxia and telangiectasias are hallmarks of this disease. The gene responsible (ATM) is located on chromosome 11. The defect in the ATM gene results in an inability to repair damaged DNA. Patients with AT have defects in both humoral and cellular immunity, and develop recurrent sinopulmonary infections and chronic lung disease (bronchiectasis). Aspiration pneumonia occurs as a result of defects in chewing and swallowing due to progressive neurological impairment.

Severe combined immunodeficiency (SCID) is incorrect because SCID is not associated with progressive cerebellar ataxia. An abnormality on chromosome 12 is incorrect because the gene for AT is located on the long arm of chromosome 11 (not 12). Friedreich ataxia is an autosomal recessive disorder characterized by progressive limb and gait ataxia, sensory loss, weakness, and dysarthria. Unlike ataxia-telangiectasia, there are no associated defects in immune function. Cystic fibrosis (CF) is an autosomal recessive disorder characterized by mutations in the CF transmembrane conductance regulator (CFTR) gene, which results in abnormal transport of sodium and chloride across an epithelium. Mucosal obstruction of the exocrine glands results in lung, liver, pancreatic, and intestinal disease. CF is not associated with neurodegeneration and progressive ataxia.

Which time of year are grass allergens likely to be the highest?
A) Spring
B) Fall
C) Summer
D) Winter
E) All year round
Answer

C. Summer

Explanation

Seasonality:

Spring: trees, some molds
Summer: grasses, molds, a few weeds
Late summer-fall: ragweed, molds

A 43-year-old woman presents with severe urticaria, facial flushing, and tongue swelling after a bee sting. Her sister had a similar reaction to contrast dye.

Which of the following describes how a bee sting causes anaphylaxis?
A) By causing an IgA-mediated reaction against protein-hapten conjugates.
B) By causing a direct activation of mediator release from mast cells, basophils, or both.
C) It’s due to a deficiency of C1 esterase inhibitor.
D) By causing an IgE-mediated reaction against proteins in the bee venom.
E) By causing an IgE-mediated event against protein-hapten conjugates.

Answer

D. By causing an IgE-mediated reaction against proteins in the bee venom.

Explanation

Anaphylaxis due to bee stings, foods, and heterologous serum (such as tetanus antitoxin) is likely due to an IgE-mediated reaction against the offending protein. IgA does not play a role in immediate hypersensitivity. Anaphylaxis due to penicillin and other antibiotics is due to IgE recognition of protein-hapten conjugates. In contrast, radiocontrast media directly activates mast cells and basophils to release the mediators of anaphylaxis. Finally, deficiency of C1 esterase results in hereditary angioedema, not anaphylaxis.

Class I HLA antigens are expressed on all cells except which of the following?
A) Reticulocytes and mature red blood cells
B) Purkinje cells
C) Reticulocytes
D) White blood cells
E) Mature red blood cells
Answer

E. Mature red blood cells

Explanation

All nucleated cells of the body express class I HLA antigens. Remember that class I HLA antigens are encoded at the A, B, and C loci of the human major histocompatibility complex on chromosome 6. The class I HLA antigens are useful in predicting results for organ transplants.

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