Secondary anetoderma associated with mastocytosis.

BACKGROUND Mastocytosis represents a wide spectrum of proliferative disorders of mast cells in the bone marrow, skin and/or internal organs. The most common manifestation is urticaria pigmentosa (UP), which is characterized by small or large brown-red maculopapules on the skin. Occasionally, elastic and collagen fibers in the lesions degenerate and result in a lax area of skin termed anetoderma. METHODS We report a 21-year-old male patient with multiple cutaneous anetodermic lesions, present since infancy, at UP sites confirmed with histochemistry. RESULTS Urinary N-methyl 24-hour histamine levels were elevated, but serum tryptase levels were within normal limits. Radiologic examination of long bones was unremarkable, as well as all other blood results. UP biopsy showed absence of epidermal involvement and increased number of mast cells located perivascularly. There was fragmentation of elastic fibers in the papillary dermis. CONCLUSIONS A patient with multiple cutaneous anetodermic lesions, presented since infancy, led to the diagnosis of UP. Such an association is rare and raises intriguing questions concerning the pathogenesis of anetoderma.