Metastatic versus primary oncocytic papillary adenocarcinoma of the endometrium: a report of a case and review of the literature.

We report a case of an oncocytic papillary adenocarcinoma of the endometrium in an 89-year-old female with vaginal bleeding. Imaging studies revealed lesions in the uterus, kidneys, pancreas, gluteus, and an enlarged portacaval lymph node. Diagnostic workup included an endometrial biopsy which showed malignant, oncocytic cells in a predominantly papillary pattern. These cells stained positive for epithelial markers (pan-cytokeratin, CK7, epithelial membrane antigen) and weakly for estrogen receptor. The cells were negative for cytokeratin 903, CAM 5.2, progesterone receptor, CD10, RCC Marker, CA-125, c-kit, and vimentin. Consultation with experts in Gynecologic and Genitourinary pathology returned a diagnosis of "adenocarcinoma compatible with metastatic renal cell carcinoma"--an intriguing possibility worthy of further exploration. To our knowledge, there are no reports in the literature of metastatic oncocytic papillary renal cell carcinoma to the endometrium. The clinical and pathologic features of oncocytic papillary endometrial lesions, including primary and metastatic processes, are reviewed.