Table of Contents
Washington University Experience | NEOPLASMS (EMBRYONAL) | Medulloblastoma, Histologically Defined | Large cell-Anaplastic (LCA) | 14A5 Medulloblastoma (Case 14) 100X 3
This is a malignant small blue cell tumor composed of sheets of pleomorphic cells that have hyperchromatic nuclei, scant cytoplasm, and high mitotic activity. Many of the nuclei are modestly enlarged and contain prominent nucleoli. However, cell-cell wrapping is not identified. Clusters of apoptotic cells are present in areas. (H&E) ---- Not shown: Tumor cells are diffusely positive for synaptophysin. GFAP staining highlights entrapped astrocytes as well as some tumor cells with glial differentiation. ---- Loss of heterozygosity of the short arm of chromosome 17 (17p), often coincident with isocentric chromosome 17q formation, is commonly found in medulloblastomas with poor response to therapy and shortened survival times. Amplification of myc genes is likewise associated with resistance to therapy and poor outcome. ---- Probes for the centromere of chromosome 2 and MYCN locus were used to evaluate the neoplasm for MYCN amplification; probes for the centromere of chromosome 8 and the MYCC locus were similarly used to evaluate for MYCC amplification and probes for the centromere of chromosome 17 and the NF1 locus (17q12) were used to evaluate for isochromosome 17q. In this case, polysomy (gain) of chromosome 2 and a normal complement of chromosome 8 were identified.; No MYC amplifications were seen. Studies to evaluate isocentric chromosome 17q were negative. This genetic pattern is considered non-specific.
