A Fatal Case of Metastatic Primary Gastric Melanoma: Diagnostic Challenges and Therapeutic Dilemmas.

Background: Primary gastric malignant melanoma (PGMM) is an exceedingly rare non-epithelial tumor. Only a limited number of cases have been documented, posing significant diagnostic and therapeutic challenges. Case Presentation: A 75-year-old man presented with cough and sputum. Computed tomography (CT) suggested a malignant tumor with multiorgan metastasis. Gastroscopy revealed multiple polypoid lesions, and histopathology confirmed melanoma. After multidisciplinary discussion, primary gastric melanoma was diagnosed. Despite aggressive treatment, the disease progressed rapidly, and the patient died six months after diagnosis. Conclusion: This case highlights the importance of early endoscopy in patients with metastatic tumors of unknown origin. Although outcomes remain poor, this report contributes to the understanding of PGMM diagnosis and management.