[Transitional cell carcinoma of the urinary bladder accompanied by signet-ring cell carcinoma: a case report].

A 58-year-old man visited our clinic with complaints of gross hematuria and pollakisuria. Cystoscopic examination revealed multiple non-papillary broad based tumors and reddish unstable mucosa in the bladder. The pathological specimen of the transurethral biopsy of the tumors showed signet-ring cell carcinoma predominantly and adenocarcinoma transforming into signet-ring cell carcinoma partially. A total cystectomy with ileal conduit urinary diversion was performed. The histopathological finding of the radical cystectomy specimen was grade 3 transitional cell carcinoma accompanied by adenocarcinoma. These findings suggest that the adenomatous metaplasia of transitional cell carcinoma in the bladder could differentiate into signet-ring cell carcinoma.