Primary gastric melanoma: case report of a rare malignancy.

We report the case of a 64-year-old white male who presented to his primary care physician with complaints of fatigue. Physical exam was unremarkable and laboratory studies revealed profound anemia, for which the patient received a transfusion. Esophagogastroduodenoscopy revealed a bleeding mass in the proximal stomach that was histologically determined to be malignant melanoma, with immunohistochemical staining demonstrating positivity for SOX10, S100, MART-1, and HMG-45. After an extensive dermatological exam no other primary lesion was identified. Whole body positron emission tomography (18-FDG-PET/CT) demonstrated pathologic uptake only in the area of the proximal stomach. For this reason, primary gastric melanoma was suspected in this patient. The patient underwent subtotal gastrectomy with mass excision followed by Roux-en-Y reconstruction. Very few cases of primary gastric melanoma have been reported. We report this case and present diagnostic criteria for primary non-cutaneous melanoma and discuss potential non-surgical therapies.