A report of amelanotic malignant melanoma of the esophagus diagnosed appropriately with novel markers: A case report

The present case study reported of amelanotic malignant melanoma of the esophagus. A 68-year-old man underwent laparoscopic distal gastrectomy for early gastric cancer diagnosis. After gastrectomy, endoscopic examination revealed a protruded lesion lying adjacent to the melanosis area of the esophagus. Histology of the biopsy specimen suggested malignancy, but the diagnosis could not be made. The patient underwent trans-thoraco-abdominal curative subtotal esophagectomy. Immunohistochemical examination of the resected specimen was negative for HBM-45 and Melan-A. However, immunohistochemical examinations of SOX10 (Sry-related HMg-Box gene 10) and KBA.62, which are not associated with melanosome, were strongly positive, and tyrosinase was notably positive. A diagnosis primary of amelanotic malignant melanoma of the esophagus that consisted of only premelanosomes was made. The present findings suggest that, in the diagnosis of malignant melanoma, SOX10 and KBA.62 may be useful, particularly in diagnosing amelanotic malignant melanoma.