PRIMITIVE CEREBRAL-TUMOR WITH RHABDOID FEATURES - A CASE OF PHENOTYPIC RHABDOID TUMOR OF THE CENTRAL-NERVOUS-SYSTEM

The rhabdoid tumor (RT) was first described as an aggressive neoplasm of unknown histogenesis affecting the kidneys of infants and young chi ldren, but has since been reported in all ages and in many other prima ry sites, including the central nervous system. It has been shown, how ever, that the histologic and cytologic features of RT can be mimicked by many other tumors of known histogenesis. For this and other reason s it remains controversial whether cases of putative extrarenal RT rep resent the same histogenetic entity as RT of the kidney (RTK), another entity or entities, or merely a diverse collection of unrelated tumor s sharing a common morphologic phenotype. The present paper describes a lethal primary cerebral tumor in a 26-month-old Hispanic boy that wa s composed predominantly of cells exhibiting the ''classic'' rhabdoid phenotype by light microscopy. Immunocytochemical and ultrastructural studies disclosed features of primitive neuroglial differentiation not seen in RTK. The findings in this case, as well as evidence from othe r studies, would seem to support the notion that primary RT of the bra in may in fact constitute a morphologic and clinicopathologic entity. However, that entity likely represents a distinctive type of neuroglia l neoplasm, more closely related to other primitive brain tumors than to RTK.