Primary malignant melanoma of the esophagus - Detection of circulating tumor cells

Primary malignant melanoma of esophagus (PMME) is a rare tumor; therefore, the prognostic factors, predictive factors, and difference in biological behaviors of cutaneous melanoma and primary esophageal squamous cell carcinoma remain uncertain. Although we did not adopt a standard therapeutic strategy, we performed surgical resection, chemotherapy, immunotherapy, and radiotherapy either alone or in combination; all procedures resulted in poor outcomes. A 67-year-old woman presented with a swallowing disorder. An esophagogastroduodenoscopy was performed, leading to diagnosis of PMME. According to the Japanese Classification of Esophageal Cancer, the pathological stage was T1b, 1y0, v0, N0, M0, stage I. KIT immunostaining was focally positive. After subtotal esophagectomy, adjuvant chemotherapy was performed, but the malignant melanoma relapsed in the mediastinum and the patient died 10 months after diagnosis. We serially monitored the patient using several new modalities, including PET/CT, metabolites of melanin: 5-S-CD, and circulating tumor cells (CTCs) by reverse transcription-polymerase chain reaction to identify the melanoma-specific gene. To our knowledge, this is the first report of a case in which CTCs in PMME were detected.