[Atypical pachydermatous cutaneous course of mastocytosis]

We describe the case of a 75-year-old man first seen in our department 32 years ago for generalized yellowish erythematous papular lesions along with an attack of pruritus, tachycardia, and flushing. A diagnosis of urticaria pigmentosa was proposed on the basis of these symptoms and the results of skin biopsy. Periodic follow-up in the intervening years included serial laboratory analyses, skin biopsy, radiological studies, bone scintigraphy, and ultrasound of the liver and spleen, with no remarkable findings. The symptoms caused by release of mediators decreased progressively. In one of the most recent visits, bone marrow aspirate and biopsy were performed, revealing multifocal infiltrates of typical CD117+ mast cells. Consequently, the hematology department diagnosed indolent systemic mastocytosis. A number of marked cutaneous changes were observed during the follow-up period: the skin currently appears thickened, indurated, redundant, and grayish, with a pachydermatous appearance. This represents an extremely rare form of cutaneous involvement in mastocytosis and only 1 case has been described in the literature.