Unexpected Distribution of cKIT and BRAF Mutations among Southern Italian Patients with Sinonasal Melanoma

BACKGROUND: Racial and geographic factors seem to affect the incidence of cutaneous and mucosal melanoma. OBJECTIVE: To investigate the occurrence of BRAF and cKIT impairments in patients with sinonasal melanoma in Southern Italy. METHODS: Eleven sinonasal melanomas were screened for BRAF mutations and cKIT alterations by immunohistochemistry (CD117), fluorescence in situ hybridization and sequencing analyses. RESULTS: A high prevalence (4/11; 36%) of BRAF mutations and lack of cKIT mutations were observed. Amplification of cKIT was found in 18% of cases; cKIT expression was detectable in 18% non-overlapping cases. No correlation between CD117 and cKIT alterations was observed. One (6%) cKIT and two (12%) BRAF mutations were detected in an additional series of 17 acral/mucosal melanomas from the same geographic areas. CONCLUSION: Mutations of cKIT are infrequent in sinonasal melanoma in Southern Italy.