S6376 The Silent Stomach: Gastric Melanoma Metastasis Revealed in a Patient With Brain Hemorrhage

Introduction: Melanoma is an aggressive malignancy arising from melanocytes, most commonly manifesting in the skin. It carries a high metastatic potential, with a predilection for the gastrointestinal tract—most frequently affecting the small bowel (50%), large bowel (31%), and anorectum (25%), with gastric involvement being notably rare. Gastric metastases are often asymptomatic or present with vague, nonspecific symptoms, frequently eluding detection until autopsy. Here, we describe a 65-year-old man who presented with a hemorrhagic stroke secondary to brain metastasis in the context of gastric melanoma. Case Description/Methods: A 65-year-old man with a history of coronary artery bypass grafting and type 2 diabetes mellitus presented with left-sided facial droop. Imaging revealed a right frontal intraparenchymal hemorrhage. Further evaluation with contrast-enhanced computed tomography (CT) demonstrated a 2-cm exophytic lesion arising from the gastric fundus, with associated soft tissue nodules along the greater curvature as well as multiple solid pulmonary nodules. Upper endoscopy revealed a friable, umbilicated gastric mass. He subsequently underwent craniotomy for resection of the intracerebral mass, with pathology confirming metastatic melanoma. His management included perioperative seizure prophylaxis, prolonged steroid taper, and multidisciplinary care involving neurosurgery, radiation oncology, and medical oncology. Notably, there was no prior history of melanoma. Discussion: Gastric metastases from melanoma are rare and typically present late, due to their nonspecific clinical manifestations. Most lesions are identified in the body and fundus of the stomach. The most commonly observed endoscopic findings of gastric melanoma are melanotic nodules with ulcerated lesions at their apex. The other 2 endoscopic patterns include submucosal tumor-like masses which are elevated lesions and also frequently show ulceration at the apex, as in this patient. The third type are mass lesions which present variable features, including areas of necrosis and melanosis, and may also appear as simple ulcers. Immunohistochemical staining for markers including S-100 and MART-1 is essential for definitive diagnosis. The aggressive nature of gastric melanoma stems from the rich vascular supply of the stomach and portends a poor prognosis if not promptly identified. Due to the wide range of endoscopic appearances, histopathological confirmation with immunohistochemistry is crucial in establishing the diagnosis.