Primary signet ring cell carcinoma of the urinary bladder. Review of the literature and report of two cases.

The signet ring cell carcinoma of the urinary bladder is a rare neoplasm; the 70 cases found in the literature pursued a fulminant and mostly fatal course; the neoplasms diffusely invaded the bladder wall without forming intraluminal growths and could not be controlled by segmental resection, radiotherapy and chemotherapy alone or in combination. We herewith present 2 cases of primary signet ring cell carcinoma of the urinary bladder--one associated with high-grade transitional cell carcinoma and in situ carcinoma--and review the literature.