Remnant Cystic Duct Carcinoma Mimicking Duodenal Carcinoma after Cholecystectomy: A Case Report.

INTRODUCTION: Cystic duct carcinoma is an uncommon subtype of gallbladder cancer, and remnant cystic duct (RCD) carcinoma after cholecystectomy is particularly rare. Due to the rarity of this disease and the anatomical alterations following cholecystectomy, early diagnosis can be challenging, making it essential to consider this entity in the differential diagnosis. We report a rare case of RCD carcinoma that became clinically apparent 3 years after laparoscopic cholecystectomy for acute cholecystitis, presenting with duodenal obstruction and initially suspected to be duodenal cancer. CASE PRESENTATION: A 53-year-old man had undergone laparoscopic cholecystectomy for acute cholecystitis with gallstones 3 years earlier at another hospital. He presented to our institution with weight loss, loss of appetite, and vomiting. Endoscopic biopsy was inconclusive; therefore, we performed open surgery to obtain a duodenal biopsy, which revealed adenocarcinoma, followed by a gastrojejunostomy. Two months later, we performed subtotal stomach-preserving pancreaticoduodenectomy, partial hepatectomy, and partial transverse colectomy. The final pathological diagnosis was RCD carcinoma with invasion into the duodenum, liver, and transverse colon. The patient was discharged on POD 24. He has remained disease-free during the first postoperative year. CONCLUSIONS: We report a rare case of RCD carcinoma after cholecystectomy. This case underscores the importance of considering RCD carcinoma as a potential biliary tract malignancy in patients presenting with unexplained symptoms following cholecystectomy.