MIXED DESMOPLASTIC PRIMITIVE NEUROEPITHELIAL TUMOR OF INFANCY - A LIGHT-MICROSCOPIC, IMMUNOCYTOCHEMICAL, ULTRASTRUCTURAL AND GENETIC-STUDY

We describe a case of a desmoplastic brain tumor which was initially r esected from the right fronto-temporal region in a 2 year-old boy. Thi s nodular, calcified tumor was vascularized by the internal carotid ar tery and the middle meningeal artery branches. Grossly, it contained s everal mucoid cysts. Light microscopy showed cords or nests of small c uboidal cells surrounded by a loose connective tissue and desmoplasic areas containing fibers and spindle cells. The cuboidal cells expresse d epithelial, neuronal and neuroendocrine markers. Some foci of spindl e cells showed glial differentiation. The tumor recurred 16 months lat er and displayed some characteristics of the small cell neuroepithelia l component, mitoses being conspicuous. Electron microscopy revealed u ndifferentiated clear cells, some containing neurosecretory granules. Karyotyping demonstrated the following formula: < 15 > 46, t(8;11) (q1 3; q11). The chromosome 11 breakpoint was different from that describe d in Ewing's sarcoma. This isolated translocation has not been previou sly reported to our knowledge. These unusual features lead us to repor t this case and to discuss its pathogenesis.