Transitional cell carcinoma of bladder originating from transitional cell carcinoma of anus.

A unique case of transitional cell carcinoma of the bladder with the primary being in the anus is reported. The patient presented with acute urinary retention from a large bladder tumor, which was thought to be primary to the bladder. Biopsy of the bladder revealed transitional cell carcinoma, microscopically indistinguishable from the primary cloacogenic carcinoma diagnosed seven years previously.