Multidisciplinary Management of Common Bile Duct Metastasis from Rectal Cancer: A Case Report of Long-Term Disease Control and Literature Review.

INTRODUCTION: Extrahepatic bile duct (EHBD) metastasis from colorectal cancer is extremely rare and remains a diagnostic and therapeutic challenge. Its clinical and radiological features often mimic primary cholangiocarcinoma and, because of the limited number of reported cases, an optimal management strategy has not yet been established. CASE PRESENTATION: A 46-year-old man underwent curative resection for rectal cancer with synchronous liver metastasis, followed by laparoscopic hepatectomy. Eight months after hepatic resection, metachronous recurrence involving the common bile duct was detected, together with local recurrence. Histopathological examination and immunohistochemical analysis of the bile duct lesion revealed a cytokeratin 7-negative, cytokeratin 20-positive, and caudal-type homeobox 2-positive profile, confirming metastasis from rectal adenocarcinoma. Because of unresectable recurrent disease, systemic chemotherapy was initiated. The patient subsequently developed obstructive jaundice due to bile duct metastasis and underwent endoscopic biliary stent placement. Although multiple stent exchanges were required because of stent occlusion and migration, biliary drainage was successfully maintained, allowing continuation of chemotherapy. The patient survived for 24 months following diagnosis of EHBD metastasis with preserved QOL. CONCLUSIONS: EHBD metastasis from colorectal cancer is a rare condition with no established treatment consensus. This case highlights that, even in unresectable disease, careful long-term management combining systemic chemotherapy with endoscopic biliary stenting may contribute to sustained biliary control and prolonged survival. Individualized treatment planning and close follow-up are essential, particularly for managing stent-related complications.