Complete Colonic Metaplasia of the Urinary Bladder and Ureters With Primary Signet-Ring Cell Adenocarcinoma of the Urinary Bladder: A Rare Occurrence

BackgroundSignet-ring cell adenocarcinoma of the urinary bladder is a rare and aggressive malignancy. Complete colonic metaplasia of urinary bladder is exceedingly rare, with only 11 patients reported in English literature.PresentationA 56-year-old woman presented with a 6-month history of voiding difficulty and hematuria. She underwent radical cystectomy with hysterectomy, bilateral salpingo-oophorectomy, and pelvic lymph node dissection, and was ultimately diagnosed as primary signet-ring cell adenocarcinoma of the urinary bladder. The entire bladder mucosa, including the ureteric mucosa, showed complete colonic metaplasia. Immunohistochemistry demonstrated a lower gastrointestinal-type immunophenotype, with positivity for KRT20 and CDX2.DiscussionThis report highlights an extremely rare instance of complete colonic metaplasia of the urothelium with subsequent development of signet-ring cell adenocarcinoma.