Lymphoepithelioma-like carcinoma of the upper urinary tract.

In this report, we summarized the clinicopathologic features of ten cases of lymphoepithelioma-like carcinoma (LELC) of the upper urinary tract (ureter n = 6; renal pelvis n = 4), a rare variant of urothelial cancer characterized by a malignant epithelial component densely infiltrated by lymphoid cells. The initial diagnosis was made on radical nephrectomy in five cases, nephroureterectomy in three cases, and ureterectomy in two others. Four patients had pathologic stage T1 (n = 2) or T2 (n = 2) tumors, and six patients had stage pT3 disease. Microscopically, all tumors contained pure (n = 3) or predominant (n = 7) LELC, which composed 60 to 80% of the entire tumor. Non-LELC tumor component was adenocarcinoma (n = 2), spindle cell carcinoma (n = 1), or high-grade conventional urothelial carcinoma (n = 4). The LELC component was characterized by indistinct cytoplasmic borders and a syncytial growth pattern. Immunohistochemical staining showed LELC to be positive for cytokeratin AE1/AE3, CK7, CK34ßE12 (rare cells), CK5/6 (rare cells), and CK20 (rare cells); rare cells were p40 positive. GATA 3 was positive in all cases in a variable proportion of cells (20-80%). Lymphoid markers showed a polyclonal proliferation of predominant T cells admixed with B cells. In situ hybridization for the HPV genome was negative in all ten cases. Survival analysis showed no differences between LELC and conventional upper urinary tract urothelial carcinoma, pT classification being the only significant prognostic parameter. Morphologic recognition and distinction from other (non-)neoplastic lesions with prominent lymphoid stroma are critical for its clinical management.