Amelanotic primary malignant melanoma of the esophagus: report of a case treated with minimally invasive esophagectomy and adjuvant chemotherapy

Amelanotic primary malignant melanoma of the esophagus (PMME) is extremely rare. We report a case of amelanotic PMME that was accurately diagnosed and subsequently treated by radical resection with adjuvant chemotherapy. A 69-year-old woman was admitted to our hospital because of dysphagia. Endoscopic examination revealed a tumor without pigmentation in the upper thoracic esophagus, and melanosis in the lower thoracic esophagus. Tumor biopsy showed proliferation of malignant spindle cells with conspicuous nucleoli. Immunohistochemically, the tumor cells were positive for melanosomes (HMB45). The tumor was diagnosed as PMME. Positron emission tomography and computed tomography showed accumulation of the tracer only in the primary lesion. The preoperative diagnosis according to the extent of the tumor, whether cancer cells have spread to lymph nodes, and whether metastasis has occurred (TNM) classification was malignant melanoma in the upper third of the esophagus, T2N0M0 stage IIA. The patient underwent minimally invasive video assisted esophagectomy in the prone position with three-field lymph node dissection. On the resected specimen, the malignant cells were positive for HMB45, KIT, and melan-A. Masson-Fontana staining demonstrated no melanin pigmentation. The patient was diagnosed with amelanotic PMME and received adjuvant chemotherapy, consisting of dacarbazine, nimustine, cisplatin, and tamoxifen. The patient showed no systemic metastasis, and is alive 18 months after the operation with no evidence of recurrence.