Rhabdoid glioblastoma

Rhabdoid phenotypic change has been described in a number of different neop lasms from diverse organ sites. These tumors share common light and electro nmicroscopic features, display a polyphenotypic immunohistochemical profile and often show cytogenetic abnormalities of chromosome 22. In the central nervous system (CNS), most rhabdoid tumors occur in the posterior fossa of very young children and are associated with a primitive neuroectodermal tum or (PNET) component and are designated atypical teratoid/rhabdoid tumors. I nfrequently, other rhabdoid tumors of the CNS have been described, includin g rhabdoid meningiomas and malignant rhabdoid tumors of uncertain histogene sis. Several examples of conventional gliomas displaying significant areas with rhabdoid morphology were also presented in an abstract by Kepes and Mo ral [1991]. although never published in final manuscript form. We now detai l the case of an 18-year-old male with an aggressive, supratentorial CNS rh abdoid tumor that was associated with an epithelioid glioblastoma and appar ently arose from areas of low-grade glioma. The rhabdoid tumor component wa s present in the original tumor but became more predominant with each of 3 successive resections. No areas of PNET were identified. Electron microscop y and immunohistochemistry showed features classic for rhabdoid tumors and cytogenetic studies demonstrated multiple tumor clones with monosomy 22. Th is case documents progressive rhabdoid transformation of a glioma, expands the spectrum of CNS tumor types that can display a rhabdoid phenotype and h ighlights the diagnostic and therapeutic challenges with this type of tumor .