[Teratoid/rhabdoid tumor of the central nervous system].

Teratoid/rhabdoid tumor is a recently introduced infantile brain neoplasm of uncertain origin clinically characterized by a most aggressive course. We describe the case of a 2-year-old boy and a 7-year-old girl, the former presenting with central fever and hemiparesis, while vomiting and headache were symptoms in the latter. A brain tumor in the right fronto-parieto-occipital and the left fronto-medial parenchyma, respectively, were found and removed by surgery. On histology, both lesions consisted of sheets of ovoid cells with prominent cytoplasm, vesicular nuclei and macronucleoli. In the second case, a spindle-cell component and bone metaplasia were also noted. Ultrastructurally, tumor cells contained whorls of intermediate filaments. Immunohistochemistry revealed a polyphenotypic expression profile including positivity for epithelial membrane antigen, vimentin and a-actin. There was no evidence of a germ-cell origin. Chromosomal translocation involving 22q11 was established cytogenetically in the first case. The teratoid/rhabdoid tumor shares many common traits with renal rhabdoid tumors and primitive neuroectodermal tumors as well as germ cell neoplasms; therefore its being an entity is debated.