title: A reappraisal of the MECT1/MAML2 translocation in salivary mucoepidermoid carcinomas.
abstract: The MECT1/MAML2 translocation is identified in a large proportion of mucoepidermoid carcinomas (MEC) of the salivary gland and is an emerging favorable prognosticator. However, there are conflicting data on this translocation's specificity, restriction to low/intermediate MEC, and strength as a prognosticator. We present our experience with the MECT1/MAML2 translocation in a large cohort of MECs to address these issues. We analyzed 55 salivary MEC and 36 potential MEC mimics (24 Warthin tumors, 5 oncocytomas, 3 squamous cell carcinomas, 2 squamoid salivary duct carcinomas, 1 lymphoepithelial cyst, 1 Schneiderian carcinoma ex papilloma) for presence of the MECT1/MAML2 translocation by fluorescent in-situ hybridization (FISH) and real-time RT-PCR. Overall, MECT1/MAML2 translocation was present in 36/55 (66%) of MEC whereas all 36 non-MEC were negative for translocation. Low or intermediate-grade MEC had a higher frequency of translocation (75%) than high-grade MEC (46%) (P=0.039). Translocation positive cases had a better disease-specific survival (log rank P=0.026) although 2 patients still died of disease. Within high-grade MEC, MECT1/MAML2 positive tumors had lower rates of anaplasia (P=0.001), and mitotic counts (P=0.012). Thus, MECT1/MAML2 translocation is highly specific for MEC and imparts a better prognosis. However, it is frequent even within high-grade MEC and can be seen in lethal cases suggesting that translocation status should not supersede conventional parameters. There are 2 distinct subgroups within high-grade MEC, and the translocation negative tumors may actually be more appropriately categorized as another tumor type (such as adenosquamous carcinoma).
authors.affiliation: Pathology and Laboratory Medicine, University of Pittsburgh, Pittsburgh, PA, USA. seethalarr@upmc.edu
authors.forename: Raja R
authors.initials: RR
authors.lastname: Seethala
authors.forename: Sanja
authors.initials: S
authors.lastname: Dacic
authors.forename: Kathleen
authors.initials: K
authors.lastname: Cieply
authors.forename: Lindsey M
authors.initials: LM
authors.lastname: Kelly
authors.forename: Marina N
authors.initials: MN
authors.lastname: Nikiforova
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D018277:Carcinoma, Mucoepidermoid / Q000235:genetics* / Q000401:mortality / Q000473:pathology; D016009:Chi-Square Distribution; D002648:Child; D018572:Disease-Free Survival; D005260:Female; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D017404:In Situ Hybridization, Fluorescence; D053208:Kaplan-Meier Estimate; D008297:Male; D008875:Middle Aged; D009367:Neoplasm Staging; D015514:Oncogene Proteins, Fusion / Q000235:genetics*; D011379:Prognosis; D012189:Retrospective Studies; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012468:Salivary Gland Neoplasms / Q000235:genetics* / Q000401:mortality / Q000473:pathology; D013997:Time Factors; D014178:Translocation, Genetic; D055815:Young Adult
chemical_list: C495418:MECT1-MAML2 fusion protein, human; D015514:Oncogene Proteins, Fusion