[Histiocytic proliferative diseases].

Proliferation of the mononuclear phagocyte system cells is the basis for histiocytic proliferative conditions (malignant histiocytosis, histiocytic "reticulosarcoma" histiocytosis X). Cells of the phagocytosing histiocyte type proliferate in malignant histiocytosis and histiocytic "reticulosarcoma), cells of the Langerhans type proliferate in histiocytosis X. According to Rappaport's classification of 1966, histiocytic "reticulosarcoma" is separated from the heterogeneous group of diffuse histiocytic lymphomas. Its morphological picture is non-distinguishable from that of malignant histiocytosis, particularly at the stage of generalization. The Letterer-Siwe disease due to its course, prognosis and special therapeutical approach should be separated from the group of conditions combined under the term "histiocytosis".