Familial urticaria pigmentosa.

Urticaria pigmentosa, characterized by cutaneous mast cell proliferation, usually occurs sporadically in childhood and resolves over a period. Rarely is the condition seen in two or more members of a family. We encountered a family in which urticaria pigmentosa occurred in four members of two generations. Skin findings were similar in all four. No systemic manifestations other than occasional flushing episodes were noted in any of the affected individuals. HLA typing was performed, but no significant correlation between affected and unaffected individuals was seen. In a review of a number of previously reported cases, we found a slight female preponderance.