Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Primary nasal melanoma is a rare tumor of unknown etiopathogenesis that occurs in adult and elderly patients usually diagnosed at advanced stages. The aim of this study was to analyze the clinicopathologic and immunohistochemical characteristics of 12 cases of primary nasal melanomas in Brazil. Twelve cases of primary nasal melanoma were analyzed histologically and by immunohistochemistry using the antibodies S-100 protein, HMB-45, Melan-A, CD63 (NKI/C3), CD68/KP1, fatty acid synthase (FASN), and Ki-67. The mean age of the patients was 60 years, and 7 of 12 patients were men. Microscopically, 10 cases presented level ill of invasion; 4 were amelanotic; and in 7, cells were epithelioid. S-100 protein and FASN were positive in all cases, whereas 9, 8, 7, and 6 cases were positive for HMB-45, Melan-A, CD63 (NKI/C3), and CD68/KP1, respectively. Ki-67 labeling index ranged from 11.45% to 28.5% of positive cells. S-100 protein is more frequently expressed in nasal melanomas than in HMB-45, Melan-A, CD63 (NKI/C3), and CD68/KP1. FASN seems to be involved in the pathogenesis of nasal melanomas, and also, it can be helpful to confirm the diagnosis. (C) 2012 Elsevier Inc. All rights reserved.165344349Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)National Council for Scientific and Technological DevelopmentFundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)