[1181] Utility of MAML2 Rearrangement Detection Using Fluorescent In-Situ Hybridization To Distinguish Glandular Odontogenic Cyst from Central Mucoepidermoid Carcinoma.

Joaquin J Garcia, E Leon Barnes, Kathleen Cieply, Sanja Dacic, Richard C Jordan, Raja R Seethala. University of Pittsburgh Medical Center, PA; University of California, San Francisco

Background: Glandular odontogenic cyst (GOC) poses diagnostic challenge because of its histomorphologic overlap with central mucoepidermoid carcinoma (CMEC). While the diagnostic value of the t(11;19) MECT1-MAML2 fusion gene has been established in distinguishing MEC from other neoplasms of the head and neck (Warthin's tumor, oncocytoma, adenosquamous carcinoma, salivary duct carcinoma), its potential use to discriminate CMEC from GOC has not been delineated.
Design: Nine cases of GOC (defined as multilocular cystic lesions lined by non-keratinized epithelium with focal plaque-like thickening and an occasional whorling appearance, scattered mucous cells and duct-like structures) and two cases of CMEC were examined. Available clinical and pathologic parameters were obtained. Cases were evaluated for MAML2 rearrangements by fluorescent in-situ hybridization (FISH) using a MAML2 – 11q21 break apart probe (SpectrumGreen-labeled BAC probe RP11-676L3 and SpectrumOrange-labeled BAC probe RP11-16K5; Children's Hospital Oakland Research Institute, Oakland, CA, USA) spanning the entire chromosome region of the MAML2 gene. At least 60 interphase tumor cell nuclei were evaluated per case. A minimum of 20% of cells with split signal was considered positive.
Results: All nine cases of GOC were gnathic (6 mandible, 2 maxilla, 1 not specified) with a median age of 56.7 years (range: 43-87) and a male to female ratio of 8:1. None of the 9 cases (0%) showed a MAML2 rearrangement by FISH. Cases of CMEC occurred in the mandibles of a 61-year-old male and 40-year-old female. Both cases of CMEC were low-grade and showed MAML2 rearrangement (100%).
Conclusions: In contrast to CMEC, MAML2 rearrangements were not detected in GOC; therefore, FISH serves as a potentially useful diagnostic tool in discriminating GOC from CMEC.
Category: Head & Neck

Tuesday, March 1, 2011 11:15 AM

Platform Session: Section G, Tuesday Morning


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