[Malignant histiocytosis in children (pathologicoanatomic study of 16 cases)].

Malignant histiocytosis is a rare neoplastic disease from the group of acute leukemias. Morphological characteristics of the disease are presented on the basis of histological, histochemical, and electron microscopic examinations of section materials from 16 cases of malignant histiocytosis in children of 6 to 14 years. Systemic focal-diffuse proliferation of tumor cells of histiocytic type of various degrees of differentiation was observed in organs and tissues. Most frequently, typical macro- and/or microscopic lesions were detected in lymph nodes, bone marrow of vertebrae, flat and tubular bones, liver, and spleen. The histiocytic nature of tumor cells was judged primarily from such signs as their capacity for phagocytosis detectable by light and electron microscopy, high diffuse cytoplasmic activity on nonspecific esterase and acid phosphatase, and features of the ultrastructure. In the establishment of the diagnosis, malignant histiocytosis had to be differentiated from Letters-Siwe disease, sinus histiocytosis with massive lymphadenopathy, lymphogranulomatosis, immunoblastic lymphosarcoma, melanoma, undifferentiated cancer.