Primary malignant melanoma of the esophagus successfully treated with nivolumab: a case report.

INTRODUCTION Primary malignant melanoma of the esophagus is a rare and aggressive disease that tends to have a poor response to chemotherapies. Previous studies have indicated that currently available treatment for primary malignant melanoma of the esophagus is insufficient. Here, we describe a case of recurrent primary malignant melanoma of the esophagus successfully treated with the immune checkpoint inhibitor nivolumab. CASE PRESENTATION An 81-year-old Japanese female presented with a 3-month history of dysphagia. She was medicated for hypertension and sarcoidosis. The patient had no past history of cutaneous, ocular, or other-site melanomas. An esophagoscopy identified a 30-mm giant tumor in the lower esophagus, at a site 30 cm from the incisors. Enhanced computed tomography revealed wall thickening measuring 30 mm in size at the middle-third of the intrathoracic esophagus, with no significant lymph node infiltration or distant metastasis. Esophageal biopsy showed proliferation of large round tumor cells and melanophages. On the basis of these findings, the patient was diagnosed with esophageal malignant melanoma and underwent esophagectomy and lymph node dissection with gastric tube reconstruction. Although the pathological diagnosis was primary malignant melanoma of the esophagus, the patient presented with multiple lymph node and bone metastases 4 months after surgery. Subsequently, treatment with nivolumab 240 mg every 2 weeks was administered as the first-line treatment. Diffusion-weighted imaging with background body signal suppression following eight courses of nivolumab revealed that the multiple lymph node and bone metastases were markedly reduced. The patient received 30 courses of nivolumab and has maintained the partial response. No severe adverse events related to the immunotherapy were recorded. CONCLUSION The current study suggests that nivolumab may be a viable option for patients with metastatic primary malignant melanoma of the esophagus. Additional evidence from future clinical trials and research is necessary to fully validate these findings.