S6221 When Common Symptoms Conceal Rare Findings: Intraluminal Ileal Metastasis in Metastatic Colorectal Cancer

Introduction: Colorectal cancer (CRC) commonly metastasizes to the liver, lungs and peritoneum. Small bowel involvement is rare. We report a case of intraluminal small bowel metastasis presenting as acute gastrointestinal (GI) bleed in a patient with metastatic CRC. Case Description/Methods: Forty-five-year-old woman with metastatic rectosigmoid cancer on chemoimmunotherapy presented with melena and abdominal pain. She was diagnosed 2 years prior with peritoneal carcinomatosis and Krukenberg tumors at presentation. Initial treatment included hysterectomy, salpingo-oophorectomy, low anterior resection, small bowel resection and peritoneal metastasis resection. Clinical course was complicated by large bowel obstruction requiring laparotomy, revealing an obstructed distal ileum adherent to pelvic implants and strictured colorectal anastomosis. A diverting loop ileostomy and blowhole colostomy were created for decompression. Prior endoscopic evaluations also showed colonic angioectasias and grade I esophageal varices. On presentation, vitals were stable. Exam showed a diffusely tender abdomen and clean ostomy site. Labs revealed Hb 6.6 g/dL, iron deficiency and elevated BUN/creatinine ratio (30). Esophagogastroduodenoscopy was unremarkable. Ileoscopy showed a patent but strictured ileostomy and 20 mm intraluminal lesion 20 cm proximal from the stoma. Biopsy confirmed metastatic adenocarcinoma (CK20+, CDX2+), consistent with the primary rectosigmoid tumor. The patient was treated supportively with blood transfusions. Due to progressive functional decline, chemotherapy was discontinued and hospice care initiated. Discussion: We report a rare case of biopsy-confirmed intraluminal small bowel metastasis in a patient with metastatic CRC presenting with GI bleed. This case highlights challenges in diagnosing and managing malignancy-related GI bleeding in patients with complex surgical and oncologic histories. While endoscopic and radiologic tools aid in localization, therapeutic endoscopy may not prevent rebleeding or improve outcomes in metastatic bleeding. As advances in treatment prolong survival, awareness of atypical metastatic sites such as the small bowel is increasingly important, especially when initial evaluation fails to identify a bleeding source. Histopathology, immunohistochemistry and molecular profiling (e.g. KRAS, BRAF) are essential to confirm tumor origin. This case supports the need for individualized surveillance strategies incorporating advanced imaging and endoscopic techniques to detect uncommon metastases and optimize symptom management.