Inverted Papillary Uroth. CA, High-Grade : Differential

Differential Diagnosis: The distinction of urothelial carcinoma with inverted growth pattern from inverted urothelial papilloma and inverted papillary urothelial neoplasm of LMP can be quite challenging due to morphologic overlap. It may be especially difficult in transurethral resection specimens due to tumor fragmentation or cautery artifact. The differential includes large nested variant of urothelial carcinoma, carcinoid tumor, and paraganglioma. (differential diagnosis continues in the next image)

This image of inverted papillary urothelial carcinoma, high-grade, shows branching, irregular, thick trabeculae composed of pleomorphic cells in the lamina propria.