Micropapillary urothelial carcinoma of the renal pelvis: report of a case and review of the literature.

Background: Micropapillary urothelial carcinoma (MPUC) is a rare variant of urothelial carcinoma (UC), which is often advanced at presentation, and carries poor prognosis. Majority of the reported cases of MPUC originate from the urinary bladder. Of over 190 MPUC cases reported in the English literature, 35 cases were of the upper urinary tract. We report a rare case of MPUC of the renal pelvis.

Case Report: A 73-year old woman presented with hematuria. She had a mass in the left renal pelvis with massive infiltration in the renal parenchyma. She underwent surgery. Pathological stage was pT4N2M1. Although she received chemotherapy, she died of disease 14 months after operation. Histologically, MPUC was found in 40% of the tumor, mostly in the infiltrating portion. Immunohistochemically, MPUC showed intracytoplasmic expression of CK7 and CK20. Distinctive expression of MUC1 was observed on the stroma-forming surface of the neoplastic clusters in MPUC. Positive staining for p53 and negative staining for bcl-2 were remarkable. In the review of the literature, overall male predominance was remarkable (M:F=5.09:1), but it was less pronounced in the upper urinary tract (M:F=1.61:1).

Conclusions: Here we present a rare case of MPUC arising in the renal pelvis with thorough review of the literature.