Primary signet-ring cell carcinoma of urinary bladder.

A case of primary signet-ring cell carcinoma of the urinary bladder is described clinically and pathologically. In this rare neoplasm the characteristic cells contain large amounts of cytoplasmic mucin which compresses the nucleus to one side. This tumor demonstrates nicely the ability of bladder epithelium to undergo metaplasia. Most previously described cases have pursued a relentlessly progressive and fatal course despite varied forms of therapy.