A case of concomitant occurrence of solitary fibrous tumor and urothelial high-grade invasive carcinoma of the urinary bladder.

Solitary fibrous tumor (SFT) is a rare mesenchymal neoplasm, most commonly arising from the pleura. It has also been recently described to occur in extrapleural sites. To our knowledge, only 16 cases of SFT have been reported in the urinary bladder to date. We report the clinicopathological features of a vesical SFT occurring in a 60-year-old man who presented a concomitant invasive high-grade urothelial cell carcinoma. No similar association has been found in the accessible literature. The morphologic and immunohistochemical clues leading to the correct diagnosis of SFT have been correlated with the data of the literature, and the differential diagnosis is briefly discussed.