Tehran University of Medical Sciences Case Reports in Clinical Practice 2538-2683 11 1 2026 08 03 31 36 Elif Terzi Sultan Abdülhamid Han Training and Research Hospital, University of Health Sciences, Istanbul, Turkey. Bülent Güleç Sultan Abdülhamid Han Training and Research Hospital, University of Health Sciences, Istanbul, Turkey. 2026 03 07 2026 05 25 Intrahepatic cholangiocarcinoma (ICC) is an uncommon and aggressive hepatobiliary malignancy characterized by high recurrence rates and poor long-term survival. Although ICC frequently metastasizes to the liver, lungs, peritoneum, and lymph nodes, metastasis to the small intestine is extremely rare. The diagnostic challenge is further increased by its often-asymptomatic course and the low specificity of radiological imaging modalities. We present a rare case of terminal ileum metastasis from ICC manifesting as focal subileus, diagnosed during postoperative surveillance. A 44-year-old male underwent left hepatic lobectomy, hepaticojejunostomy, and cholecystectomy for well-differentiated ICC (pT2N1) in July 2023. Despite adjuvant capecitabine therapy, follow-up computed tomography revealed segmental pathological wall thickening of the terminal ileum with luminal narrowing, proximal dilatation, and associated mesenteric lymphadenopathy. Colonoscopic biopsy was not feasible due to the lesion’s location. Further evaluation suggested malignancy, raising suspicion of metastatic ICC versus primary small bowel adenocarcinoma. The patient underwent right hemicolectomy with partial small bowel resection. Pathology demonstrated poorly differentiated adenocarcinoma (pT2) with lymphovascular and perineural invasion, and isolated tumor cells in one lymph node. Loss of MLH1 and PMS2 expression indicated MSI-H status. The findings were consistent with metastatic ICC. Postoperative recovery was complicated by intra-abdominal ascites requiring catheter drainage. The patient was referred to medical oncology for further management. Metastasis of ICC to the terminal ileum is exceptionally rare but should be considered in patients presenting with unexplained small bowel obstruction or mural thickening during postoperative follow-up. Complete surgical resection can be effective when the patient’s performance status allows. Multidisciplinary evaluation is essential for accurate diagnosis, differentiation from primary small bowel tumors, and appropriate oncological treatment planning. https://crcp.tums.ac.ir/index.php/crcp/article/view/1177 https://crcp.tums.ac.ir/index.php/crcp/article/download/1177/773