Recurrent primary leptomeningeal astrocytoma of the lumbosacral spinal cord resembling schwannoma. A case report.

Primary leptomeningeal astrocytoma has been considered to be derived from ectopic glial cells in the leptomeninges. A case of recurrent primary leptomeningeal astrocytoma of the lumbosacral spinal cord is described. The original tumor was localized in the extramedullary space at the level of the 12th thoracic vertebra, and was solely composed of interlacing bundles of monomorphous spindle-shaped cells. The tumor was therefore diagnosed as schwannoma. The recurrent tumor removed one year after the first operation showed two distinct histologic patterns with increased nuclear atypia and mitosis. Namely, both schwannoma-like areas and astrocytomatous areas were observed. Silver impregnation clearly demonstrated an alveolar pattern in the schwannoma-like area. Immunohistochemically, the tumor cells revealed a positive reaction for glial fibrillary acidic protein. This case particularly emphasizes the usefulness of silver impregnation in differential diagnosis from schwannoma.