Tubulocystic ovarian clear cell carcinoma with abundant fibrous stroma: malignant clear cell adenofibroma.

We report a case of tubulocystic ovarian clear cell carcinoma (OCCC) with abundant fibrous stroma associated with an endometriotic cyst. Most OCCC show a small amount of fibrous stroma; however, the tumor presented in this case had abundant stroma, that qualifies it as a malignant clear cell adenofibroma. This unusual type of clear cell carcinoma may be misinterpreted as a benign lesion or as metastatic carcinoma on frozen section. In permanent sections, the stromal invasive foci are focal, small and subtle. Therefore, extensive sampling of the specimen to search for evidence of invasion is recommended for a fibrous ovarian tumor that appears benign on gross examination.