Medicine>>>>>Allergy and Immunology
Question 1#

A 20-year-old woman develops urticaria that lasts for 6 weeks and then resolves spontaneously. She gives no history of weight loss, fever, rash, or tremulousness. She denies any use of medication or drugs; the hives are not related in time to the ingestion of fresh fruits, shellfish, peanuts, or dairy products. Physical examination shows no abnormalities except for a few residual hives in the antecubital fossae.

Which of the following is the most likely cause of the urticaria? 

A. Connective tissue disease
B. Hyperthyroidism
C. Chronic infection
D. Food allergy
E. Not likely to be determined

Correct Answer is E


Urticaria (hives) presents as well-circumscribed wheals with raised serpiginous borders. Individual lesions usually persist less than 24 hours, only to be replaced by other hives at other locations. The process may be triggered by a specific antigen such as food, drugs, or pollen. It may also be bradykinin mediated, such as in hereditary angioedema, or complement mediated, as in hypocomplementemic vasculitis. Some chemical agents cause urticaria by direct (ie, non-IgE mediated) effect on mast cells, either by mast cell degranulation (narcotics, radiocontrast agents) or by affecting arachidonic acid metabolism (aspirin, NSAIDs). These causes should be sought in the history; however, in the great majority of patients with urticaria, a cause is never found. Very rarely, urticaria accompanies illnesses such as chronic infection, myeloproliferative disease, collagen vascular disease, or hyperthyroidism. Usually, however, the patient with one of these illnesses displays clinical evidence of the underlying process.