Amelanotic Gastric Metastases From Melanoma Presenting as Gastrointestinal Bleeding Shortly After Diagnosis: A Case Report

Melanoma is an aggressive malignancy with a high propensity for metastasis; however, clinically apparent involvement of the gastrointestinal tract is uncommon. We report a case of metastatic melanoma involving the stomach that presented as gastrointestinal bleeding shortly after initial diagnosis. A patient with recently diagnosed melanoma with nodal metastasis presented with melena and symptomatic anemia. Esophagogastroduodenoscopy revealed multiple gastric mucosal lesions that were notably amelanotic, lacking the characteristic pigmentation typically associated with melanoma. Histopathological and immunohistochemical evaluation confirmed metastatic melanoma, and imaging findings were concerning for advanced disease. The presence of pneumatosis raised suspicion for mucosal compromise and possible early perforation, highlighting the potential severity of gastrointestinal involvement. Gastrointestinal metastases from melanoma are often clinically silent and may present with nonspecific symptoms, leading to delayed diagnosis. This case is notable for early symptomatic presentation and the presence of amelanotic lesions, which may be easily overlooked during endoscopic evaluation. The absence of pigmentation can pose a diagnostic challenge and requires a high index of suspicion in patients with a history of melanoma. Early endoscopic evaluation and tissue diagnosis are essential for timely recognition and management. Clinicians should maintain a high index of suspicion for gastrointestinal metastases in melanoma patients presenting with unexplained anemia or bleeding, even in the absence of classic endoscopic features.