We report the case of a 44-year-old man with pT3bN1aM0, stage IIIb primary malignant melanoma of the left shoulder. He was treated with tumor resection, lymph node dissection, and postoperative adjuvant chemotherapy. Three years later, abnormal accumulation on PET-CT was identified in the intrathoracic esophagus. We conducted upper endoscopy ; the pharynx and intrathoracic esophagus showed a black, diffuse, flat lesion. Pathological studies showed atypical cells with melanin pigment, and immunostaining for S-100 and HMB-45 were performed. The lesion was diagnosed as metastatic malignant melanoma of the esophagus. The patient was treated with molecular therapy consisting of BRAF and MEK inhibitors. The intrathoracic esophageal lesion was extremely responsive to this treatment.
