ABSTRACT
Purpose To study the clinicopathologic features and differential diagnosis of primary mucosal melanoma of the nasal cavity (PMMNC).Methods 17 cases of PMMNC diagnosed from January 2003 to September 2016 were studied by clinical pathological analysis and immunohistochemical staining,and relevant literatures were reviewed.Results 73％ of the PMMNC was characterized by unilateral nasal congestion and intermittent epistaxis and 61％ of the PMMNC occurred in the nasal septum and nasal side wall.Microscopically,the organizational structure and morphology were complex and diverse,which had several cell types including epithelioid cell type (6cases,35.3％),spindle cell type (3 cases,17.6％) and snall cell type (5 cases,29.4％),the other 3 cases (17.6％)were mixed cell type.Mitotic activity and tumor necrosis were more likely to be seen in PMMNC,among other clinicopathological features with a small amount of fibrous stroma and melanoma and rich blood vessels.The immunohistochemical study showed that the positive rate of S-100 and HMB-45 were both 93.8％(15 cases) and those of Melan-A and vimentin were both 87.5％ (14 cases),while CK and EMA were both negative (16 cases).Conclusion PMMNC is a rare disease and the phenotype of S-100,HMB-45,Melan-A and vimentin are useful for diagnosis of PMMNC.