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PubMedDate not supplied

Choroid plexus carcinomas and rhabdoid tumors: phenotypic and genotypic overlap.

Five of six poorly differentiated choroid plexus carcinomas identified at our institution contained cells displaying a rhabdoid phenotype. Immunoperoxidase stains showed focal positivity for cytokeratin, epithelial membrane antigen, glial fibrillary acidic protein, S100, and vimentin. The MIB-1 proliferative index ranged from 7.0% to 27.1%. All six tumors were p53 positive. Only the one child with Li-Fraumeni syndrome had a p53 germline mutation. Electron microscopy verified choroid plexus differentiation and the co-existence of rhabdoid cells. Of the five studied, four had deletions of chromosome 22 [three with monosomy 22 and one with del(22)(q12)]. Thus, there was a phenotypic and genotypic overlap between choroid plexus carcinomas and rhabdoid tumors.

Adolescent↗

PubMedDate not supplied

Rhabdoid glioblastoma.

Rhabdoid phenotypic change has been described in a number of different neoplasms from diverse organ sites. These tumors share common light and electron-microscopic 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 tumor (PNET) component and are designated atypical teratoid/rhabdoid tumors. Infrequently, other rhabdoid tumors of the CNS have been described, including rhabdoid meningiomas and malignant rhabdoid tumors of uncertain histogenesis. Several examples of conventional gliomas displaying significant areas with rhabdoid morphology were also presented in an abstract by Kepes and Moral [1991], although never published in final manuscript form. We now detail the case of an 18-year-old male with an aggressive, supratentorial CNS rhabdoid tumor that was associated with an epithelioid glioblastoma and apparently arose from areas of low-grade glioma. The rhabdoid tumor component was present in the original tumor but became more predominant with each of 3 successive resections. No areas of PNET were identified. Electron microscopy and immunohistochemistry showed features classic for rhabdoid tumors and cytogenetic studies demonstrated multiple tumor clones with monosomy 22. This case documents progressive rhabdoid transformation of a glioma, expands the spectrum of CNS tumor types that can display a rhabdoid phenotype and highlights the diagnostic and therapeutic challenges with this type of tumor.

Adolescent↗