Malignant melanoma in the stomach treated with endoscopic submucosal dissection: a case report

The initial appearance of malignant melanoma localized in the stomach has never been reported previously. We encountered a patient with gastric melanoma in the stomach, which was histologically confirmed to be confined to the mucosa.

Case presentation: The patient, when in her 40s, had undergone surgery for malignant melanoma of the left heel. However, there were no detailed records of pathological findings. The patient had a 4-mm black elevated lesion in her stomach observed on esophagogastroduodenoscopy after the eradication of Helicobacter pylori. A year later, esophagogastroduodenoscopy showed that the lesion had increased to 8 mm. A biopsy was performed, but no malignancy was found; the patient continued to be followed up. Esophagogastroduodenoscopy performed at the 2-year follow-up revealed that the melanotic lesion had increased to 15 mm, and biopsy was performed and revealed a malignant melanoma.

Clinical discussion: Endoscopic submucosal dissection was performed for gastric malignant melanoma. The margin of the resected malignant melanoma was negative; vascular and lymphatic invasions were not observed, and the lesion was confined to the mucosa.

Conclusion: We suggest that even if the first biopsy of a melanotic lesion shows no evidence of malignancy, the lesion should be closely monitored. This is the first reported case of endoscopic submucosal dissection of localized gastric malignant melanoma confined to the mucosa.