A rare case of primary mucosal melanoma involving the oropharynx

Melanomas are malignant tumors arising from melanocytes. A vast majority of melanomas occur on cutaneous surfaces. Rarely, melanomas can also be found in various extracutaneous sites where melanocytes are scarcely present. Here, we present a 58-year-old Caucasian man who was referred to the ENT department of the Antwerp University Hospital with the complaint of a mass in the left oropharynx and a palpable cervical lymph node. Fiberoptic endoscopy showed a black mass arising from the left pharyngeal wall at the superior border of the oropharynx. Fluorodeoxyglucose positron emission tomography computed tomography (FDG-PET-CT) and magnetic resonance imaging (MRI) of the liver revealed liver metastases and lymph node metastases along the coeliac trunk branches and in the left neck. A transoral biopsy confirmed the diagnosis of primary mucosal melanoma, and the tumor was staged as pT4aN2M1. A full-body inspection by the dermatology department did not reveal any suspected skin lesions. Immunotherapy with nivolumab and ipilimumab was started. To conclude, mucosal melanomas are rare, yet very aggressive and have a dismal prognosis. The epidemiologic, genetic, and biologic differences between mucosal and cutaneous melanomas have adverse implications for both treatment and prognosis of mucosal melanoma. Imaging, including PET scan, is of great importance in evaluating the extent of the lesion and distant metastases.