Slow growing flat-type primary malignant melanoma of the esophagus treated with cap-assisted EMR

We report a rare case of flat-type primary malignant melanoma of the esophagus treated with endoscopic mucosal resection (EMR). A 64-year-old woman was referred for examination of a small pigmented lesion located in the mid esophagus. On endoscopy, the lesion exhibited almost no change in size over the year. Cap-assisted EMR was performed en bloc. The histopathological findings showed atypical melanocyte proliferation in the basal layer, spindle cells, and epithelioid cell proliferation with nuclear enlargement and a few mitotic figures. Histopathological examination confirmed the diagnosis of primary malignant melanoma. Immunostaining for S-100 protein and HMB-45 antibody were positive, and the Ki-67 index was low. The patient was discharged without additional surgical resection and/or chemotherapy. The patient had no symptoms and no signs of recurrence 20 months after EMR. There has been no report on a slow growing esophageal melanoma. It is difficult to estimate the malignant behavior of this case.