Sarcoma with true epithelial differentiation secondary to irradiated glioblastoma.

Glioblastoma multiforme rarely shows true, immunohistochemically confirmed, epithelial differentiation. Furthermore, radiotherapy may induce cerebral sarcomatous tumors, and postsurgery glioblastoma irradiation may give rise to secondary gliosarcomas. We report a case of a 48-year-old male operated on a primary glioblastoma, followed by radiotherapy. A local recurrence occurred 23 months later that was operated too, and a second diagnosis of a fibrosarcoma with true epithelial differentiation was made. Primary systemic neoplasms were largely excluded. The patient died shortly after, and postmortem showed another cerebral dural-attached mass corresponding to a sarcoma without epithelial differentiation, and leptomeningeal seeding composed of malignant epithelial elements only. Cytogenetics, however, disclosed the second tumor to be similar to the primary one.