MOLECULAR DETECTION OF MECT1-MAML2 FUSION GENE IN MUCOEPIDERMOID CARCINOMA WITH ORDINARY AND VARIANT HISTOLOGY: A STUDY USING ARCHIVAL PARAFFIN EMBEDDED TISSUE
Mucoepidermoid carcinoma (MEC) has been characterized by t (11; 19)(q21;
p13). This chromosomal translocation has been recently shown to generate a MECT1-
MAML2 fusion gene. MEC can pose diagnostic challenges when they are of high-grade,
of variant histologic appearance and occurring in an unusual site. The aim of this study
was to evaluate the frequency of the MECT1-MAML2 fusion gene among primary
salivary gland MECs and extrasalivary gland MECs, together with some histological
variants and its role as a possible diagnostic adjunct, comparing the salivary gland
tumors including Warthin's tumor(WT)，pleomorphic adenoma(PA)，and adenoid cystic
carcinoma(ACC). Using a reverse transcription-polymerase chain (RT-PCR)-based
approach, we assayed for the MECT1-MAML2 transcript in 39 cases for which paraffin-
embedded tumor tissue with adequate RNA was available. These included 19 MECs，10
WTs， five PAs， and five ACCs. The MECT1-MAML2 fusion gene transcript was
detected in 16 (84.2%) of 19 MECs. These positive cases included two cases of MEC with
WT-like areas，a sclerosing MEC and a clear cell MEC. Three negative cases were high-
grade MECs. Two of them were not easy to distinguish from squamous cell carcinoma.
The MECT1-MAML2 fusion gene was negative in all cases of WT，PA and ACC. The
potential usefulness of MECT1-MAML2 fusion gene expression as a molecular marker in
the diagnosis of MEC is supported
