The value of immunocytochemistry in distinguishing between clear cell carcinoma of the kidney and ovary

Renal clear cell carcinoma rarely metastasizes to the ovary potentially mimicking a primary ovarian clear cell carcinoma. The immunocytochemical profiles of the two tumors were compared. Control groups of ovarian endometrioid and serous adenocarcinomas were also examined using the same antibody panel. Paraffin sections were studied with the immunocytochemical technique using eight antibodies. Renal clear cell carcinomas were positive for vimentin (8/12 cases): CK5/6 (0/12), 34 beta E12 (1/12), Ber-Ep4 (5/12), CA125 (0/12), ER (1/12), and PGR (1/12). Ovarian clear cell carcinomas showed positivity with vimentin (1/10 cases), CK5/6 (2/10), 34 beta E12 (10/10), Ber-Ep4 (10/10), CA125 (8/10), ER (7/10), and PGR (6/10). Endometrioid adenocarcinomas were positive for vimentin (9/10 cases), CK5/6 (8/10), 34 beta E12 (10/10), Ber-Ep4 (9/10), CA125 (9/10), ER (9/10), and PGR (10/10). Eight serous adenocarcinomas were positive in all cases for all the antibodies except CK5/6 (7/8 cases) and 34 beta E12 (7/8 cases). All the tumors reacted for epithelial membrane antigen. This immunohistochemical panel allows clear cell carcinomas of kidney and ovary to be distinguished. The latter has a greater phenotypic similarity with serous and endometrioid adenocarcinomas than with renal clear cell carcinoma demonstrating yet again that these ovarian tumors share a common histogenetic origin.