Primary Malignant Melanoma of the Oesophagus Treated With Immunotherapy: A Case Report and Scoping Review of the Literature.

[PURPOSE] Primary malignant melanoma of the oesophagus is extremely rare. Given this, there is a paucity of evidence to guide treatment decisions. Traditionally, treatment has included standard modalities of surgery, chemotherapy, and/or radiotherapy. Immunotherapy has revolutionised the treatment of cutaneous melanoma; however, molecular studies have provided conflicting results regarding whether the underlying mechanisms driving melanoma response to immunotherapy are reproduced in mucosal and, more specifically, oesophageal melanomas. The evidence base for treatment decisions in primary malignant melanoma of the oesophagus remains limited due to the small number of reported cases, with only 374 cases reported in the world literature up to 2022.

[CASE REPORT AND LITERATURE REVIEW] We present the case of an 81-year-old Caucasian female patient, previously in good health aside from gastro-oesophageal reflux. The patient presented with dysphagia and proceeded to CT and endoscopy showing a large mid-to-distal oesophageal mass. Endoscopic biopsies revealed a poorly differentiated epithelioid malignancy, with immunohistochemical studies confirming melanoma. FDG-PET revealed metastatic deposits in the skeleton as well as mesenteric nodes. The patient was commenced on treatment with ipilimumab and nivolumab 18 days following diagnosis. Despite receiving only one cycle of immunotherapy, the patient demonstrated remarkable resolution of symptoms as well as complete resolution of PET-avidity of all local and metastatic disease and remains in remission 2 years following diagnosis. Scoping review of the literature identified just three case series and 18 case reports of patients with primary oesophageal melanoma treated with immunotherapy This case is now the third case reported in the literature of patients with oesophageal melanoma metastatic at diagnosis, who have entered long-term complete remission following sole treatment with immunotherapy and the only case to enter remission following a single cycle of treatment.

[CONCLUSION] We report our experience with one of the few reported cases of metastatic primary malignant melanoma of the oesophagus treated with immunotherapy, with encouraging results. We would encourage reporting of further cases in order to better understand the role of immunotherapy in oesophageal melanoma.