RESUMO
Objective:To investigate the clinicopathologic features and molecular genetics characteristics of sinonasal tract mucosal malignant melanomas(STMMMs)in elderly patients.Methods:The clinicopathological features, immunohistochemical features and BRAF, C-KIT, NRAS mutations of STMMM in ten elderly patients were retrospectively analyzed.Results:Among the 10 patients, 5 were female and 5 were male.The patients were aged 65-81 years, with an average age of(72.5 ± 8.5)years.The lesions in 7 cases were located in the nasal cavity and paranasal sinuses, and in the other 3 cases were located in the nasopharynx.The morphologies of tumor cells under microscope was complex and diverse, showing plasma cell-like, rhabdomyoblast-like, small cell-like, epithelial-like, and spindle cell-like morphologies.Immunohistochemically, HMB-45 and S-100 were generally positive in 10 cases, and the positive rate of Melan A was 70.0%.The genes detection data showed no mutations in BRAF or NRAS genes in all the 10 cases, while C-KIT exon 11 c. 1666_1667insA mutation was found in one case, and the remaining 9 cases were wild-type for C-KIT.All the 10 cases were followed up for 4~50 months.Three cases survived so far.Conclusions:STMMM in elderly patients are rare and easy to be misdiagnosed.Immunohistochemistry and genetic testing provide guidance for accurate diagnosis and targeted therapy.