[1002] Primitive Neuroectodermal Tumors in Patients with Testicular Germ Cell Tumors Usually Resemble Pediatric-Type Central Nervous System Embryonal Neoplasms and Lack Chromosome 22 Rearrangements

TM Ulbright, EM Hattab, S Zhang, Y Ehrlich, RS Foster, LH Einhorn, L Cheng. Indiana University School of Medicine, Indianapolis, IN

Background: Primitive neuroectodermal tumors (PNET) are one of the most frequent types of “non-germ cell” tumor in patients with testicular germ cell tumors (TGCT). When identified in metastatic sites after cisplatin-based chemotherapy, they are associated with a poor prognosis. Improved treatments are therefore required, making it important to understand the biology of these neoplasms. We therefore analyzed the morphologic, immunohistochemical and molecular biologic features of 14 PNETs from 14 TGCT patients.
Design: Two primary and 12 metastatic PNETs from 14 separate patients were identified. The hematoxylin and eosin-stained slides were reviewed and the tumors classified based solely on the light microscopic features into recognized categories of either central nervous system (CNS) PNETs or peripheral (Ewing sarcoma-type) PNETs. Immunostains directed against INI1, CD57, S-100, NeuN, WT1, neurofilament, CD99, GFAP, synaptophysin, chromogranin, AE1/AE3 cytokeratin, Fli-1 and collagen IV were performed for each case. Each case was also analyzed for chromosome 22 rearrangements using a FISH-based breakapart probe method.
Results: Nine tumors resembled medulloepithelioma, 3 medulloblastoma/supratentorial PNET, one neuroblastic tumor with abundant neuropil and true rosettes and 1 small cell embryonal tumor/peripheral PNET. INI1 was diffusely and strongly positive in all cases whereas the other stains, except for cytoplasmic WT1 (which showed substantial reactivity in most tumors), were mostly focal to negative, including CD99 (8 negative, 6 focal)) and Fli-1 (all negative). The most consistently reactive neuroendocrine marker was CD57. One tumor, classified as medulloepithelioma, was scored positive for chromosome 22 translocation (22% rearranged cells) and the remaining 13 were negative, including the one case that resembled peripheral PNET.
Conclusions: We conclude that PNETs derived from TGCTs mostly resemble CNS PNETs and generally lack evidence of the chromosome 22 translocation of peripheral PNETs. Future treatment strategies should take these findings into account.
Category: Genitourinary (including renal tumors)

Monday, March 22, 2010 1:00 PM

Poster Session II # 97, Monday Afternoon


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