The transitional cells of benign Brenner tumor are positive for CK7 (shown here), p63, GATA3, uroplakin, thrombomodulin, EMA, and CEA. One-third of cases show scattered chromogranin-positive cells. CK20 is negative or only focally positive. The image shows solid nests of transitional epithelium in a dense fibromatous stroma. Image courtesy of: Woo Cheal Cho, MD, Dept. of Pathology, Hartford Hospital, Hartford, Connecticut.