Systemic cold urticaria in a five-year-old boy.

A 5-year-old white boy had a history of generalized urticaria on total body exposure to a cold environment. Standard ice cube testing was negative. Plasma analysis revealed the presence of cryofibrinogen. Systemic cold challenge with serial plasma assays for complement, histamine, and prostaglandin D2 disclosed an elevation and peak of plasma histamine and prostaglandin D2 levels after the onset of generalized urticaria with no change in serum complement levels.