Histiocytosis, malignant: A term sometimes used to refer to a group of tumors including monocyte-related leukemias (for example, acute monocytic leukemia, acute myelomonocytic leukemia), extramedullary monocytic tumor, and histiocytic sarcoma. Treatment is by radiation and chemotherapy, and in some cases bone-marrow transplantation.
See also histiocytosis.
