Solitary fibrous tumor of the urinary bladder: report of a case with long-term follow-up and review of the literature.

Solitary fibrous tumor (SFT) is a neoplasm typically arising in the pleura. Yet, extrapleural cases have been described and are a common cause of diagnostic pitfalls, especially when met in unusual sites. We report the clinical and pathological features of a case of SFT arising in a rather unusual site, the urinary bladder, the seventh reported to date in the English literature and the first with long term follow-up. Differential diagnosis from other spindle cell neoplasms of the bladder can be problematic. Prognosis of this neoplasm is obscure and long-term follow-up is required for all cases of solitary fibrous tumor. Solitary fibrous tumor is a rare mesenchymal tumor of the urinary bladder, but should always be considered in the differential diagnosis of spindle cell neoplasms encountered in the lower genital tract.