Cutaneous malignant histiocytosis: a clinical and histopathologic study of eight cases, with immunohistochemical analysis.

Eight cases of autopsy-proved malignant histiocytosis (MH) are reported, in which cutaneous involvement was a prominent finding at initial clinical presentation. In two patients, the disease remained confined to the skin for significant periods before systemic dissemination appeared. Immunohistochemical analysis of cutaneous infiltrates of MH showed uniform negativity of the atypical cells for lysozyme, immunoglobulin light chain, glycogen, and chloroacetate esterase content. In five cases, cytochemical stains for acid phosphatase, butyrate (nonspecific) esterase, chloroacetate esterase, and peroxidase activity were performed on bone marrow aspirates containing malignant cells; all demonstrated diffuse positivity for acid phosphatase and nonspecific esterase, and negativity for peroxidase and chloroacetate esterase. Touch-imprint preparations of cutaneous lesions in one of these cases yielded identical results. These findings indicate that cytochemical methods are preferable to immunohistochemical technics in identification of histiocytic malignancies and that foci of skin involvement may provide a useful source for such diagnostic evaluation.