Exp Clin Endocrinol Diabetes 2013; 121 - OP6_36
DOI: 10.1055/s-0033-1336645

Results of Mutation and Rearrangements Detection in Air-Dried FNA Smears in a Routine Diagnostic Setting of Patients with Nodular Thyroid Disease

M Eszlinger 1, M Neustadt 1, I Ruschenburg 2, A Neumann 3, R Glaubitz 3, R Paschke 1
  • 1Universitätsklinikum Leipzig AöR, Klinik für Endokrinologie und Nephrologie, Leipzig, Germany
  • 2MVZ wagnerstibbe für Gynäkologie, Reproduktionsmedizin, Zytologie, Pathologie und Innere Medizin GmbH, Einbeck, Germany
  • 3Amedes Medizinisches Versorgungszentrum für Laboratoriumsmedizin, Mikrobiologie und Genetik Hamburg GmbH, Hamburg, Germany

Results for the detection of rearrangements and point mutations have thus far only been reported in retrospective and two prospective studies, which required additional fresh FNA material. This is the first report of preliminary results of their diagnostic detection in routine air-dried FNA smears.

RNA and DNA was extracted from 134 consecutive routine air-dried FNA smears (43 FNA smears with follicular neoplasia (FN), 70 FNA smears with microfollicular proliferation (MFP), and 21 FNA smears with the cytological diagnosis of papillary carcinomas (PTC). 2 PAX8/PPARG and 1 RET/PTC 3 rearrangements were detected by qPCR, while 18 BRAF and 9 RAS point mutations were detected by pyrosequencing.

Only 0.7% and 3.0% of routine air-dried FNA samples did not allow analysis of a point mutation or rearrangements, respectively. For the 43 FN-FNA, 70 MFP-FNA and the 16 PTC-FNA, NRAS mutations could be detected in 1/5/0 FNA samples, respectively. HRAS mutations were detected in 1/1/0 samples, respectively. A KRAS mutation was detected in 1/0/0 sample, and BRAF mutations were detected in 1/0/16 samples, respectively. PAX8/PPARG was detected in 0/2/0 samples, while RET/PTC 3 was detected in 0/1/0 samples, respectively. In total, 9.3% FN-FNA, 12.9% MFP-FNA, and 76.2% PTC-FNA samples harbored a mutation, respectively.

These results demonstrate that the detection of rearrangements and point mutations can be successfully performed in a routine diagnostic setting. The high percentage of BRAF positive FNA smears with the cytological diagnosis PTC, should result in more primary total thyroidectomies instead of diagnostic lobectomy followed by completion thyroidectomy after histologic diagnosis. The analysis of borderline cases with MFP can lead to important additional information with likely clinical consequences, whereas the molecular analysis of FN samples provided further specific arguments for a diagnostic lobectomy for mutation positive samples.