DISSEMINATED METASTATIC MELANOMA OF UNKNOWN ORIGIN fiRST DIAGNOSED IN THE ORAL CAVITY WITH NEAR RESOLUTION AFTER IMMUNOTHERAPY AND SUBSEQUENT IMMUNE-RELATED SEQUALAE

Abstract

Herein, we report an atypical clinicopathological presentation of amelanotic melanoma first diagnosed in the oral cavity of a 68-year-old man. The tumor was immunopositive for HMB45 and S-100, and weakly positive to Melan A. PET (positron emission tomography) and CT (computed tomography) scans demonstrated widespread organ and bone metastases, obviating surgical intervention. Standard immunotherapy was instituted with ipilimumab and nivolumab. At 3-weeks, near resolution of the oral lesion was evident and repeat imaging showed resolution of the left lung lesions and marked reductions in size of other affected sites. The patient subsequently experienced and recovered from multiple immune-related adverse events, including autoimmune carditis, which was managed with steroid administration. Following subsequent immunoregimens and 4 months since the initial diagnosis, the patient succumbed to sudden apparent cardiac arrest. Historically, surgery, chemotherapy, and radiotherapy to manage mucosal melanoma have yielded poor long-term outcomes, necessitating alternative efforts to improve patient care. Immunotherapy is an emerging modality for management of late-stage melanoma and has shown promising results to extend overall survival.