Lymphoepithelioma-like carcinoma of the renal pelvis: a case report with immunohistochemical analysis and in situ hybridization for the Epstein-Barr viral genome.

Lymphoepithelial carcinoma is a relatively common malignancy in the nasopharynx, but it rarely occurs at other sites. Described herein is the first case of a renal pelvic neoplasm that closely resembled lymphoepithelial carcinoma, with analyses of histology, immunophenotype, in situ hybridization for the Epstein-Barr viral genome, and flow cytometric DNA ploidy. The tumor was detected in an 70-year-old Japanese man who presented with hematuria Histologic examination showed an undifferentiated round or spindle cell carcinoma (cytokeratin 7+, cytokeratin 20+, epithelial membrane antigen+, vimentin-) with abundant lymphocytes (predominantly UCHL-1+ T cells), plasma cells, and macrophages in and around the tumor cell nests. The tumor was limited to the pelvis, with a minute focus of carcinoma in situ. No Epstein-Barr viral genomic sequences were detected by in situ hybridization. The tumor had an aneuploid DNA content. The patient remains well without disease 6 years after surgery and radiotherapy. Recognition of this type of renal pelvis carcinoma is important to avoid misdiagnosis.