Metastatic melanoma is a highly aggresive disease, with a high affinity for gastrointestinal tract metastasis, that amount up to 60% in autopsy reports. However, gastric metastasis are un common, leading up to less than 150 cases in some metaanalysis.

We present the case of a 83-year-old woman that was admitted into our Internal Medicine Department due to weight loss and anemia due to iron deficiency, without evidence of a gastrointestinal bleeding. As a part of the diagnostic study, an esophagogastroduodenoscopy (EGD) was performed. Located at the proximal region of the greater curvature, an exophytic nodular lesion was found. It was composed of several, smaller, ulcerated nodules, resembling a bunch of grapes. The mucosa surrounding the ulceration was apparently normal, leading to submucosal tumour as a first diagnosis. (Figure 1). The analysis via microscope showed epithelial cells grouped in bundles and immunohistochemical staining was positive for Sox10, vimentin, HMB-45, Melan-A and S-100 leading to the histopathological diagnosis of melanoma.

Completing the study, a computerized tomography was performed. There, pulmonary, hepatic and gastric metastasis were described, as well as a lesion in the right breast that was compatible with the primary melanoma. The hepatic lesion was the largest with a diameter of 10cm located on the right lobe, while the gastric lesions found on the EGD also were present on the study. (Figure 2)

After the diagnosis, pembrolizumab, a PD-1/PD-L1 inhibitor was started. However, the patient passed away three months after the diagnosis.

Gastric metastasis of melanomas are a seldom finding, characterized by bundles of ulcerated lesions surrounded by normal mucosa. Although it is frequent for these lesions to present melanosis, our lesion was amelanic. Positivity for S-100 and HMB-45 confirms the histopathologic diagnosis.