Histopathologic examination showed a high-grade neoplasm composed of polygonal, epithelioid cells with significant nuclear pleomorphism (Figure 3) and a high mitotic index. Areas of tumor necrosis and brownish pigmentation were present. On immunohistochemical analysis, tumor cells were diffusely positive for S100 protein and HMB-45 (Figure 4 ). A diagnosis of sinonasal melanoma (SNM) was made. Radiography of the chest, ultrasonography of the abdomen, and a total-body computed tomographic scan ruled out regional and distant metastases. The cosmetic outcome was excellent, and after a 40-month follow-up period, the patient was still free of disease.