Pineocytoma with neuronal differentiation demonstrated immunocytochemically. A case report.

Stereotactic biopsies were obtained from a tumor in the pineal gland of a 37 year old man. Histological and smear preparations were studied using conventional staining techniques as well as immunocytochemical methods with monoclonal antibodies to glial fibrillary acidic protein (GFAP), the neurofilament proteins (NFP), the presynaptic vesicle protein synaptophysin as well as with antisera to neuronal specific enolase (NSE). The tumor was classified as a pineocytoma. The tumor cells uniformly contained no cytoplasmic GFAP but NFP, NSE and synaptophysin as shown by the immunocytochemical techniques. The pineocytoma could thus be subclassified as a pineocytoma with neuronal differentiation. The patient subsequently succumbed due to a hemorrhage into the tumor and autopsy confirmed the biopsy findings. We conclude that immunocytochemical techniques may prove invaluable in the subclassification of tumors of the pineal region.