Operative Management of Stage IV Melanoma Metastasizing to the Sigmoid Colon

Document Type

Conference Proceeding - Restricted Access

Publication Date

5-8-2026

Abstract

Malignant melanoma most commonly metastasizes to lymph nodes, lung, liver, brain, and bone. Within the gastrointestinal tract, melanoma most frequently metastasizes to the small bowel; however, colonic metastases have been reported on rare occasion. Importantly, metastasis to the alimentary tract may occur several years after initial diagnosis. Therefore, endoscopic surveillance is critical when there is a high index of suspicion for gastrointestinal spread. Here, we present a case of malignant melanoma with operative resection of metastasis to the sigmoid colon.

The patient is a 69-year-old female diagnosed with malignant melanoma of the left extremity. After imaging and wide local excision with sentinel lymph node biopsy, the final stage was T4, N0, M0 (IIC disease). Proprietary genetic testing subclassified the tumor to meet "high-risk" criteria and was treated with adjuvant immunotherapy. After two months a new skin lesion on the chest was discovered, biopsied and found to be metastatic melanoma. CT imaging revealed extensive metastatic disease to her neck, mediastinum, lungs, peritoneum, and bilateral adrenal glands. She was transitioned to ipilimumab and nivolumab, and later started on nivolumab and relatlimab-rmbw combination therapy. Follow up imaging revealed near-resolution at all sites of disease with the exception of hypermetabolic activity in the sigmoid colon. She did endorse light rectal bleeding, but no abdominal pain or change of bowel habits. Colonoscopy revealed a mass positive for metastatic melanoma.

Here, we present the case of a 69-year-old female with stage IV melanoma metastasizing to the colon who underwent operative intervention for control of the disease. It is important to note that persistently pigmented lesions do not always indicate failure of treatment. According to prior studies, including a multicenter retrospective cohort study, resection of metastatic disease on immunotherapy has been correlated with improved overall survival. Therefore, metastasectomy in patients with stage IV disease should be discussed on a selective basis.

Comments

2026 Research Day Corewell Health West, Grand Rapids, MI, May 8, 2026. Abstract 2107

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