Primary Malignant Melanoma of the Gastroesophageal Junction Treated With Immunotherapy: A Case Report.

Introduction: Primary malignant melanoma of the esophagus constitutes 0.1% to 0.5% of all primary malignant esophageal neoplasms. Melanocytes are present within the squamous epithelium of the esophagus in the stratum basale layer with melanocytosis rare within the esophagus. Primary esophageal melanoma is aggressive and has a poor survival rate; 80% of patients have metastatic disease at diagnosis. Resection surgery is usually first-line treatment for localized primary malignant esophageal melanoma, but recurrence rates remain high. Tumor-specific immunotherapy has shown promising results. We report a case of primary malignant esophageal melanoma with metastasis to the liver treated with immunotherapy.

Case presentation: A 66-year-old woman presented with 2 months of progressive dysphagia and 3 episodes of hematemesis the previous night. Endoscopic examination showed a hypervascular distal esophageal mass. Biopsy was positive for S-100, SOX-10, and HMB-45 and showed rare mitotic figures with scattered pigment, consistent with melanoma. She was scheduled for esophagectomy initially, but instead pursued immunotherapy after liver metastasis was diagnosed during preop magnetic resonance imaging. Immunotherapy consisted of 8 cycles of pembrolizumab, followed by 4 months nivolumab and ipilimumab. The patient remains in remission 3 years after completing immunotherapy.

Discussion/conclusions: Our patient was diagnosed with primary malignant esophageal melanoma of the distal esophagus with metastasis to the liver, a presentation that typically has a poor prognosis. Despite this, remission was achieved with immunotherapy without surgical intervention. Only a small number of cases of primary esophageal melanoma treated with immunotherapy have been reported-one showcasing tumor stabilization following several cycles of therapy with eventual metastasis, while our patient had a stable response to treatment. Further exploration of medical management with immunotherapy should be conducted, as it represents an alternative treatment for patients who do not have the option of surgical management.