Epithelial-Myoepithelial Carcinoma: Frequent Morphologic and Molecular Evidence of Preexisting Pleomorphic Adenoma, Common HRAS Mutations in PLAG1-intact and HMGA2-intact Cases, and Occasional TP53, FBXW7, and SMARCB1 Alterations in High-grade Cases

We hypothesized that there is a relationship between the preexisting pleomorphic adenoma [PA]), histologic grade of epithelial-myoepithelial carcinomas (EMCAs), and genetic alterations. EMCAs (n=39) were analyzed for morphologic and molecular evidence of preexisting PA (PLAG1, HMGA2 status by fluorescence in situ hybridization, FISH, and FGFR1-PLAG1 fusion by next-generation sequencing, NGS). Twenty-three EMCAs were further analyzed by NGS for mutations and copy number variation in 50 cancer-related genes. On the basis of combined morphologic and molecular evidence of PA, the following subsets of EMCA emerged: (a) EMCAs with morphologic evidence of preexisting PA, but intact PLAG1 and HMGA2 (12/39, 31%), (b) Carcinomas with PLAG1 alterations (9/39, 23%), or (c) HMGA2 alterations (10/39, 26%), and (d) de novo carcinomas, without morphologic or molecular evidence of PA (8/39, 21%). Twelve high-grade EMCAs (12/39, 31%) occurred across all subsets. The median disease-free survival was 80 months (95% confidence interval, 77-84 mo). Disease-free survival and other clinicopathologic parameters did not differ by the above defined subsets. HRAS mutations were more common in EMCAs with intact PLAG1 and HMGA2 (7/9 vs. 1/14, P

from #ORL-AlexandrosSfakianakis via ola Kala on Inoreader http://ift.tt/2As7FO5