Complete remission in metastatic primary malignant melanoma of the esophagus with nivolumab: a case report

BACKGROUND: Primary malignant melanoma of the esophagus is a rare form of mucosal melanoma with a poor prognosis. While immune checkpoint inhibitors have recently extended overall survival in metastatic melanoma, data on their effects on primary malignant melanoma of the esophagus are limited because of its rarity. Here, we report the first case of long-term complete remission of metastatic primary malignant melanoma of the esophagus after nivolumab monotherapy. CASE PRESENTATION: A 79-year-old Asian man with a history of prostate cancer, gallbladder cancer, deep vein thrombosis, hypertension, and diabetes mellitus presented with gross hematuria. Cystoscopy revealed a solitary tumor on the right posterior wall of the bladder, and transurethral resection of bladder tumor was performed. Pathology was consistent with metastatic melanoma. A pigmented submucosal tumor-like growth in the esophagus was discovered on esophagogastroduodenoscopy. Computed tomography showed widespread metastases. The patient was diagnosed as having primary malignant melanoma of the esophagus with metastases to the stomach, subcutaneous tissue, lung, bladder, pleura, and peritoneum. Complete remission was achieved after seven cycles of triweekly nivolumab monotherapy. While nivolumab was discontinued because of kidney injury, the patient has remained tumor-free for over 4 years without further treatment. CONCLUSION: Immune checkpoint inhibitors may have astonishing curative effects in selected populations. More research is warranted to identify factors that increase the likelihood of achieving complete remission in primary malignant melanoma of the esophagus as well as in other melanomas.