Malignant histiocytosis and Letterer-Siwe disease. Neoplasms of T-zone histiocyte with S100 protein

Abstract

Eight cases with malignant histiocytosis (MH), two cases with systemic Letterer-Siwe disease, and one case with sarcomatous variant of MH were studied clinicopathologically. Characterization of neoplastic histiocytes was performed by immunohistochemical staining for S100 protein, lysozyme, and nonspecific cross reacting antigen with carcinoembryonic antigen (NCA). The immunohistochemical characteristics of histiocytes were S100+lys-NCA- in eight MH and two Letterer-Siwe disease cases and S100-lys+NCA+ in the sarcomatous variant of MH. MH and Letterer-Siwe disease were considered to have derived from a specific S100+ histiocytic cell lineage (T-zone histiocyte with S100 protein) independent of the monocyte--macrophage system, from which a sarcomatous variant was derived. Leukemic change of MH was discussed with special reference to the maturation and differentiation of T-zone histiocytes.