Xanthoma disseminatum: a rare normolipemic xanthomatosis.

Xanthoma disseminatum (XD) is a rare benign histiocytic disorder with extensive cutaneous and mucous membrane xanthomas in normolipemic patients. We describe the 9-year course of a 25-year-old white man who presented with multiple brownish-reddish papulous skin tumors that developed over 3 years and remained relatively constant, with spontaneous regression and progression of individual lesions since. In addition, there was asymptomatic xanthomatous infiltration of the epipharnyx and symptomatic infiltration of the synovial membrane of the left knee joint leading to restriction of movement. Histologically, the corium was infiltrated by large lipid-storing macrophages, polynucleated histiocytic giant cells of the Touton and the foreign body type. Immunhistochemically, the lipid-storing cells could be classified as macrophage/monocyte derived cells distinctly different from Langerhans' cells without proliferative activity. The clinical picture and course as well as laboratory findings indicating normolipidemia made it possible to differentiate XD from other normolipemic xanthomatosis, especially juvenile xanthogranuloma, eruptive histiocytoma, and histiocytosis X. The etiology of XD is still unknown. It is possible to differentiate xanthoma disseminatum from malignant histiocytosis X by the clinical picture and immunhistochemical studies. Thus it is no longer justified to administer cytostatic treatment for this disorder.