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Pediatric embryonal tumor with epithelial immunophenotype showing absence of hSNF5/INI1 expression
Keiichi Sakai1, Hiroaki Shigeta, Yoshifumi Ogiso
1Department of Neurosurgery, Shinshu University School of Medicine, Asahi 3-1-1, Matsumoto 390-8621, Japan. skeiichi@hsp.md.shinshu-u.ac.jp
Case Report:
A case of a histologically unclassified brain tumor in a 32-month-old boy is reported. He presented with vomiting, appetite loss, and right motor weakness. MR images revealed a huge mass in the left frontoparietal region that was enhanced after the administration of Gd-DTPA. The mass was removed three times because of its recurrence.
Results:
Histologically, the tumor was composed largely of small-undifferentiated round cells without any patterns of differentiation. Immunohistochemically, the tumor cells were positive for cytokeratin and focally for epithelial membrane antigen (EMA). Glial fibrillary acidic protein (GFAP), S-100 protein and neuronal markers were negative. Electron microscopic investigations demonstrated no evidence of specific differentiation. MIB-1 staining index was 10-40%. The origin of the tumor was not detected. Expression of the hSNF5/INI1 of this tumor was not detected by reverse transcription-polymerase chain reaction (RT-PCR). The patient has been in a good condition for 7 years after the first operation.
Conclusions:
Based on the immunohistochemical findings, the tumor was descriptively diagnosed as an embryonal tumor with an epithelial immunophenotype. The hSNF5/INI1 gene has recently been reported to act as a tumor suppressor in atypical teratoid/rhabdoid tumors. The hSNF5/INI1 gene may lead to tumorigenesis in this case.
