CK7-negative and CK20-Positive intestinal- type gastric adenocarcinoma metastasis to the bladder: A case report of an unprecedented phenotype

The majority of bladder tumors (around 90 %) are urothelial carcinomas, while metastatic secondary tumors are extremely rare, comprising less than 2 % of cases. Gastric adenocarcinoma rarely metastasizes to the bladder, and these metastases typically exhibit a CK7-positive, CK20-negative phenotype. To date, there have been no reports of gastric cancer metastasis to the bladder that displays a CK7-negative and CK20-positive profile. This article presents a rare case of a patient who had previously undergone subtotal gastrectomy for gastric adenocarcinoma and later presented with macroscopic hematuria, where a CK7-negative, CK20-positive secondary adenocarcinoma was detected in the bladder.