Primary malignant histiocytosis of the brain: a clinical, radiological and morphological study with cytological and immunohistochemical demonstration of atypical histiocytes.

Clinical, radiological and morphological findings in the case of a 79-year-old patient with a primary malignant histiocytosis of the brain are reported. The tumor was exclusively situated in the brain as proven by autopsy and was spreading on the inside of the lateral ventricles. The demonstration of atypical histiocytic cells in the CSF and the immunohistochemical demonstration of lysozyme, alpha 1-antitrypsin and alpha 1-antichymotrypsin which are typical for histiocytes, underline the histiocytic origin of the tumor.