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.