Thorotrast-associated gliosarcoma. Including comments on thorotrast use and review of sequelae with particular reference to lesions of the central nervous system.

The occurrence of a glioblastoma with sarcoma, a gliosarcoma, in the left frontal-temporal area of a 49-year-old woman with a history of Thorotrast exposure, is described. Thorotrast-laden histiocytes and free Thorotrast material were found in both components of the tumor. An overlying, adherent dural cranial lesion was found to contain massive deposits of Thorotrast embedded in a dense fibrotic and sclerotic stroma with focal calcification. These features are typical of "Thorotrastoma." Thorotrast stains greenish-brown with hematoxylin and eosin and appears as refractile granular particles of relatively uniform size either within histiocytes or as free material. The radioactivity of the deposits was confirmed through the use of a scintillation counter, and 232 thorium was definitively identified though the use of scanning electron microscopy with energy-dispersive X-ray analysis. Immunohistochemical studies of the tumor demonstrated glial fibrillary acid protein (GFAP) immunoreactivity in areas of glioma and focal vimentin and actin immunoreactivity in areas of sarcoma. Thorotrast-associated lesions of the central nervous system (CNS) are infrequently reported, and a Thorotrast-associated gliosarcoma has not yet been reported. The use of Thorotrast, its radiobiology, and sequelae are reviewed with particular emphasis on lesions occurring in the CNS.