General data
This was a retrospective clinical study. In total, 36 patients with head and neck mucosal malignant melanoma were treated in [removed for blind peer review] between January 2015 and October 2018. They were all treated surgically and with the diagnosis confirmed pathologically as mucosal melanoma. Immunohistochemical staining was performed on the tumor tissue after surgery (routine staining process in the pathology department, and the results were summarized and analyzed). All 36 patients were included; samples from 24 patients underwent immunohistochemical staining of CD4, CD8, PD-1, and PD-L1; staining of CD3 was performed in samples from 12 patients. All of the related data were obtained from our otolaryngology head and neck surgery department. In total, 16 patients were male and 20 were female with age ranging from 5 to 78 years. The follow-up time ranged from 22 to 67 months. The primary sites of the tumor were the nasal cavity (17), paranasal sinus (3), the nasal cavity and paranasal sinus (12), and the nasopharynx (4). According to the eighth edition of TNM staging, there were 18 cases of T3N0M0, 16 of T4aN0M0, and 1 each of T4aN1M0 and T4bN0M0.