BRAF Mutation (V600E) in Papillary Carcinoma Identified on LBC-Processed Thyroid Aspiration Biopsies.
Guido Fadda, Esther D Rossi, Maurizio Martini, Celestino P Lombardi, Gian Franco Zannoni, Valerio G Vellone, Anna M Ferrara, Alfredo Pontecorvi, Guido Rindi. Catholic University, Rome, Italy
Background: Activating mutations of the BRAF gene are observed in a proportion of papillary thyroid carcinoma (PTC). The most common mutations involves the V600E locus and has been identified in 70% of the classic variant of PTC and more than 80% of the tall cell variant. But, it has not been detected in benign lesions and in the majority (80%) of the follicular variant of PTC. The identification of BRAF V600E mutation in a PTC diagnosed on liquid based cytology (LBC) may be useful to predict the prognostic outcome of PTC and to direct the clinical management of patients. To determine the utility of the mutational analysis in thyroid fine needle aspiration (FNA),10 cases with histology were examined.
Design: Ten cases of thyroid carcinomas on LBC-FNA,underwent BRAF mutational analysis. The needle with the material was rinsed in a haemolytic-preservative solution Cytolit (Hologic Co). The cells were spun at 1500 rpm (rotations per minute) then the sediment transferred in the PreservCyt (Hologic Co) solution to be processed with the T2000 automated processor according to the manufacturer's recommendations. The resulting slide was fixed in 95%ethanol and stained with Papanicolau. DNA extraction was performed on FNA sample ThinPrep 2000 using the QIAamp tissue kit (Qiagen). After PCR amplification the fragment spanning the Braf exon 11 and 15 were treated with EXOSap (UBS, Sial) and directly sequenced using BigDye Terminator kit v3.1 (Applied Biosystem) using the same primers of the PCR amplification, in an ABI PRISM 3100 Genetic Analyzer (Applied Biosystems).
Results: Six cases (60%) showing a BRAF gene mutation were identified in LBC-FNA. Among them, 3 were histologically multifocal PTC with nodal metastases, 1intraglandular microPTC, 2tall cell variants of PTC multifocal with positive nodes. The remaining 4 cases without BRAF mutation were 2follicular variants ,1columnar cell carcinoma and 1PTC.
Conclusions: The V600E BRAF mutation can be successfully identified on LBC material even a few months after the FNA. This parameter may predict the clinical behavior of cases diagnosed as PTC on FNA and allowing a correct surgical strategy without repeating the biopsy.
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Wednesday, March 2, 2011 1:00 PM
Poster Session VI # 49, Wednesday Afternoon