Searching for RET/PTC rearrangements and BRAF V599E mutation in thyroid aspirates might contribute to establish a preoperative diagnosis of papillary thyroid carcinoma R. Domingues*, E. Mendonc¸a   , L. Sobrinho à and M. J. Bugalho* ,à *Centro de Investigac¸a˜o de Patobiologia Molecular,   Departamento de Patologia Morfolo´ gica e, à Servic¸o de Endocrinologia, Instituto Portugueˆ s de Oncologia Francisco Gentil, Centro Regional de Oncologia de Lisboa, SA, Lisboa, Portugal Accepted for publication 29 October 2004 R. Domingues, E. Mendonc¸a, L. Sobrinho and M. J. Bugalho Searching for RET/PTC rearrangements and BRAF V599E mutation in thyroid aspirates might contribute to establish a preoperative diagnosis of papillary thyroid carcinoma Objective: Searching for multiple molecular markers in thyroid aspirates appears to be a promising approach for establishing a preoperative diagnosis of papillary thyroid carcinoma (PTC). Methods: Based on this hypothesis, a total of 63 samples from 55 patients, were collected at random. RNA was extracted from the residue cells inside the needle used for fine needle aspiration cytology (FNAC) and thereafter molecular analysis was carried out both for RET rearrangements (type 1, 2, 3) and BRAF codon 599 mutation mole- cule. Results were compared with the cytological and histopathological diagnoses in 24 patients submitted to surgery. Results: 58% PTCs presented a genetic alteration either RET/PTC rearrangement, BRAF V599E mutation or both: three cases of PTCs (25%) presented a RET/PTC rearrangement; three cases of PTCs (25%) presented a BRAF V599E mutation and in one case (8%) both alterations were identified. Conclusions: The present results suggest that searching for multiple molecular markers in thyroid aspirates may enhance the accuracy of FNAC and refine preoperative diagnosis of PTC. Keywords: fine needle aspiration cytology, RET rearrangements, papillary thyroid carcinoma, BRAF mutation Introduction Thyroid nodules are very frequent. 1 However, only roughly 5% are malignant. Papillary thyroid carci- noma (PTC) is the most common thyroid carcinoma. 2 Fine needle aspiration cytology (FNAC) is the only test that can provide a definitive preoperative diagnosis of malignancy. However, an indeterminate or suspicious result can pose diagnostic and management difficul- ties. 3 In order to circumvent this problem, the use of molecular techniques, such as RT-PCR, has been attempted to analyse products from FNAC. 4–9 Until recently, somatic rearrangements of the proto- oncogene RET were the sole molecular marker con- sistently related to PTC. 10–12 Evidence for a somatic point mutation at codon 599 of BRAF, leading to the substitution of a valine for a glutamic acid, in a high percentage of PTCs 13–15 extended the spectrum of molecular markers associated with PTC. Searching for RET rearrangements in thyroid aspir- ates has already been reported as a useful tool in order to establish a preoperative diagnosis of PTC. 16 Herein we analysed thyroid aspirates both for RET rearrangements (type 1, 2 and 3) and BRAF codon 599 mutation. Results were compared with the cytological diagnosis and final histopathology. Materials and methods A total of 63 samples (55 from thyroid aspirates and eight from lymph node aspirates) corresponding to 55 Correspondence: Rita Sofia Cardoso Domingues, Centro de Investigac¸a˜o de Patobiologia Molecular (CIPM), Instituto Portugueˆs de Onc- ologia Francisco Gentil, Centro Regional de Oncologia de Lisboa, SA, R. Prof. Lima Basto, 1099-023 Lisboa, Portugal. Tel.: +351 21 7229800; Fax: +351 21 7229895; E-mail: rdomingues@ipolisboa.min-saude.pt Cytopathology 2005, 16, 27–31 ª 2005 Blackwell Publishing Ltd 27