Answer to last month's Clinical Quiz

Question:
A 13 years old student girl complained of mild pain at both ankles and elbows and lower abdominal colic in the past three weeks. She noted a skin rash in both lower limbs in the past few days. She was previously well and had taken no medication prior to the appearance of the rash and pain. There had been a history of a mild sore throat a month ago. The preliminary investigations upon hospitalisation were essentially normal except for a trace of albumen and red cells detected in urine and an elevated ESR on blood examination.

The presence of a palpable erythemato-urticarial and purpuric rash most prominent in the lower legs with features of arthritis, gastrointestinal symptoms, or both, and occurring in children, is characteristically enough to diagnose Henoch-Schonlein Purpura. There are no absolute criteria for separating it from other forms of cutaneous vasculitis. The particular complication of nephritis also gives it a special importance. Some will consider the presence of elevated serum IgA with IgA deposition along vessels of skin and kidney diagnostic. It may be preceded by upper respiratory infection. Papular urticaria or insect bite allergy are seldom confused with this condition. Papular urticaria is often quite itchy and it is not accompanied by systemic signs and symptoms. Erythema multiforme can be one of the differential diagnoses but it rarely confines itself to the lower limbs only. Usually, the size of the lesions will have a larger range of variations and target-like lesions can be found in typical erythema multiforme. Erythema nodosum presents with an indurated deep seated nodular lesions with tenderness (as it is a form of septal panniculitis or inflammation of the deeper subcutaneous fat) and purpura is not a feature found in erythema nodosum.