Recurrent malignant histiocytosis with cerebrospinal involvement--case report.

A 61-year-old male presented with recurrent malignant histiocytosis of the brain manifesting as nausea and headache. Malignant histiocytosis is a disorder of proliferating histiocytes characterized by a rapidly progressive and fatal course, but central nervous system involvement is relatively rare. Magnetic resonance (MR) imaging demonstrated cerebrospinal fluid (CSF) dissemination of histiocytes as a low-intensity area on the T1-weighted image with marked gadolinium-diethylenetriaminepenta-acetic acid enhancement and a high-intensity area on the T2-weighted image. CSF cytological examination revealed an increased level of atypical histiocytes. Brain and spine irradiation, and intrathecal methotrexate and prednisolone administration induced remission. MR imaging is particularly useful for the diagnosis of meningeal dissemination of malignant histiocytosis.