Histiocytoma; histiocytoma proliferans; histiocytoma malignum: (clinical and morphological observations).

In a group of 112 cases of histiocytic neoplasms treated 1960--1973 103 benign tumors (histiocytoma), 3 semimalignant tumors (histiocytoma proliferans), and 6 malignant ones (histiocytoma malignum) were diagnosed. Clinical and morphological examinations indicate that under the influence of stimuli histiocytoma may undergo a biological transformation developing into less mature forms such as histiocytoma proliferans and histiocytoma malignum. The treatment of malignant tumors consisted in their removal together with a wide margin or adjacent tissues. In 2 cases enlarged lymph nodes were removed but no metastases were found. In one case death occurred 3 years after operation as a result of distant metastases.