Malignant Brenner Tumor
Malignant Brenner tumors show cytologically malignant areas (usually resembling high-grade urothelial carcinomas of the urinary tract) with stromal invasion. The tumor cells are arranged in solid sheets, irregularly shaped nests, or branching trabeculae. They usually have high-grade features, including pleomorphic hyperchromatic nuclei, brisk mitotic activity, central necrosis producing comedocarcinoma-like pattern, and desmoplastic stromal response. A benign Brenner tumor is seen on the left in this image. The appearance of the malignant component may be transitional (seen here), squamous, glandular, undifferentiated or mixed.