S4336 A Triple Hit: Multifocal Gastrointestinal Involvement of Metastatic Melanoma

Introduction: Melanoma frequently metastasizes, but clinically apparent gastrointestinal (GI) involvement is rare, occurring in only 1%–5% of cases despite being found in up to 60% at autopsy (Blecker et al. and Das Gupta et al.). Among GI sites, the small intestine is most commonly affected, while gastric and colonic involvement is less frequent. We present a rare case of multifocal GI metastatic melanoma involving the stomach, duodenum, and sigmoid colon. Case Description/Methods: A 59-year-old man presented with chest pain, dysphagia, and weight loss. Computed tomography imaging revealed bilateral pulmonary nodules, mediastinal and hilar lymphadenopathy, and metastases to the liver, spleen, adrenal glands, peritoneum, and retroperitoneum. Computed tomography-guided biopsy of a mediastinal mass confirmed metastatic melanoma. Esophagogastroduodenoscopy and colonoscopy were performed for further evaluation of his dysphagia and weight loss. Esophagogastroduodenoscopy showed an 8 mm gastric body ulcer and a 6 mm duodenal ulcer. Colonoscopy revealed a 30 mm ulcerated, infiltrative sigmoid mass with stigmata of recent bleeding. All 3 lesions were biopsied and confirmed to be metastatic melanoma. The patient began combination immunotherapy with nivolumab and ipilimumab, followed by maintenance nivolumab. Discussion: Multifocal GI involvement by melanoma is exceptionally rare. This case underscores the importance of considering GI metastases in melanoma patients presenting with new symptoms such as dysphagia, bleeding, or weight loss. Endoscopic evaluation remains essential in identifying and managing metastatic lesions, especially in instances of bleeding. Simultaneous upper and lower GI involvement highlights the aggressive nature of the disease.