A Tumor of Intrigue: Undifferentiated Carcinoma With Osteoclastic Giant Cells of the Urinary Bladder.

Undifferentiated carcinoma with osteoclastic giant cells (UCOGC) of the urinary bladder is a recently described entity classified as a subtype of poorly differentiated urothelial carcinoma, which is a form of invasive urothelial carcinoma. It is an extremely rare and aggressive malignancy that occurs predominantly in elderly men. The rarity of this neoplasm and its morphological similarity to other giant cell-rich lesions may present diagnostic challenges. Here, we present a case of urinary bladder carcinoma with a biphasic appearance. Histomorphological examination and immunohistochemical studies are important for identifying this entity and differentiating it from other carcinomas with similar features, given the significant prognostic and therapeutic differences among these entities.