MECT1-MAML2 Fusion Transcript Expression in Lung Mucoepidermoid Carcinoma
Neda Kalhor, Junya Fujimoto, Jaime Rodriguez, Lauren A Byers, Merrill S Kies, Wayne L Hofstetter, Adel K El-Naggar, Diana Bell. University of Texas MD Anderson Cancer Center, Houston, TX
Background: Mucopeidermoid carcinoma (MEC) of tracheobronchial tree is a rare primary lung malignancy. Over the last two decades, an association between salivary gland MEC and MECT1-MAML2 gene fusion has become well established. This translocation appears to confer a low grade histology and favorable prognosis in MEC. However, its frequency and clinicopathological significance in tracheobronchial MECs is not well established due to their low incidence.
Design: Thirteen cases of tracheobronchial mucoepidermoid carcinoma were retrospectively analyzed for MECT1-MAML2 fusion transcript by a nested-PCR assay using formalin-fixed, paraffin-embedded specimens. All patients underwent surgical resection of the tumor except for one patient with a high grade MEC who had multifocal involvement of the tracheobronchial tree. Clinical data of the patients were obtained from their clinical records. Histologically, cases included in this study consisted of 10 low grade and 3 high grade MECs.
Results: Eight of eleven (73%) cases with successfully amplified DNA were positive for MECT1-MAML2 fusion transcripts. All the fusion-positive tumors were low grade. It is interesting to note that 7/11 cases were misdiagnosed on biopsy material. The most common diagnoses mistaken for MEC in biopsy material were adenocarcinoma and squamous cell carcinoma.
Conclusions: We demonstrate that low grade tracheobronchial MECs are frequently (88%) associated with MECT1-MAML2 fusion transcript. The presence of MAML2 rearrangement can be used as supportive evidence in diagnosis of tracheobronchial MECs.
Wednesday, March 6, 2013 1:00 PM
Poster Session VI # 290, Wednesday Afternoon