A reappraisal of the MECT1/MAML2 translocation in salivary mucoepidermoid carcinomas

Am J Surg Pathol. 2010 Aug;34(8):1106-21. doi: 10.1097/PAS.0b013e3181de3021.

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).

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adolescent
  • Adult
  • Aged
  • Aged, 80 and over
  • Carcinoma, Mucoepidermoid / genetics*
  • Carcinoma, Mucoepidermoid / mortality
  • Carcinoma, Mucoepidermoid / pathology
  • Chi-Square Distribution
  • Child
  • Disease-Free Survival
  • Female
  • Gene Expression Regulation, Neoplastic
  • Humans
  • In Situ Hybridization, Fluorescence
  • Kaplan-Meier Estimate
  • Male
  • Middle Aged
  • Neoplasm Staging
  • Oncogene Proteins, Fusion / genetics*
  • Prognosis
  • Retrospective Studies
  • Reverse Transcriptase Polymerase Chain Reaction
  • Salivary Gland Neoplasms / genetics*
  • Salivary Gland Neoplasms / mortality
  • Salivary Gland Neoplasms / pathology
  • Time Factors
  • Translocation, Genetic*
  • Young Adult

Substances

  • MECT1-MAML2 fusion protein, human
  • Oncogene Proteins, Fusion