they include proliferations of monocytes ( acute monocytic leukemia ) , proliferations of tissue macrophages or histiocytes ( histiocytic sarcoma and its disseminated form , malignant histiocytosis ; familial histiocytoses ; and multicentric reticulohistiocytosis ) , proliferations of langerhans ' cells ( histiocytosis x ) , and proliferations of as yet undefined cells of the mononuclear phagocyte system ( sinus histiocytosis with massive lymphadenopathy ) .
C0023381
familial
C0019621
histiocytosis x