The remaining lower pole rim of kidney tissue is shown. Initial pathologic reading was malignant small round blue cell tumor invading into perinephric adipose tissue but not through Gerota's fascia. There was extension beyond the renal hilar plane with positive perinephric lymph nodes and liver metastasis. The adrenal gland was normal.
The Ewing family of tumors, characterized by small round blue cells, are rare lesions usually seen in the pediatric age range. They include Wilms tumor, embryonal rhabdomyosarcoma, primitive neuroectodermal tumor (PNET), neuroblastoma and lymphoma. The immunophenotypic and cytogenetic studies needed to differentiate these tumors are being conducted on this lesion.
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