Solitary Fibrous Tumor of Bladder
Solitary fibrous tumors (SFTs) can involve the urinary bladder. They may be discovered incidentally or present with hematuria and urinary obstruction. This low power view shows a spindle cell proliferation in a dense collagenous stroma. Given their rarity, SFTs are often mistaken for sarcomatoid carcinoma or sarcomas. Immunoreactivity for CD34 and bcl-2 and lack of staining with cytokeratins, EMA, and smooth muscle markers is diagnostic.