Transitional cell carcinoma of the urinary bladder with pseudosarcomatous stroma.

An 84-year-old man who complained of hematuria had transurethral resection of a large polypoid tumor in the urinary bladder. Pathologic examination showed an invasive, moderately differentiated transitional cell carcinoma with numerous atypical mesenchymal cells in its stroma. The latter cells failed to stain immunohistochemically for epithelial markers and were interpreted as reactive or pseudosarcomatous in nature. Transitional cell carcinomas with pseudosarcomatous stroma should be distinguished from bladder tumors with a neoplastic spindle cell component such as sarcomatoid carcinomas and carcinosarcomas.