Objectives

Oncocytic follicular neoplasm (OFN) of the thyroid gland are a significant clinical problem, due to indeterminate invasive properties of the tumor without surgery. Diagnostic methods are increasingly complemented by molecular tests (including BRAFV600E and RAS gene mutations). There is no clear opinion on the prevalence of BRAFV600E and RAS mutations among OFNs and the possibility of using these mutations as predictor of tumor’s malignancy. The aim of the study was to investigate the possibility of using BRAFV600E and RAS mutations detection in fine-needle aspiration cytology (FNAC) to determine the malignant nature of OFN.
Methods
We included 85 FNAC OFNs after reviewing the clinical, cytological features and pathology follow-up. Detection of BRAFV600E and RAS gene mutations was carried out by Real-time PCR.
Results
Among 85 OFNs there were 54 oncocytic adenomas (OA), 31 oncocytic carcinomas (OCA). No BRAFV600E mutation was detected in any case. The presence of a mutation in the RAS gene was detected in 13 OFN samples, with no significant difference in the detection of RAS mutation in OA and OCA. In the group of OCA, the presence of RAS mutation was detected in 6 out of 31 cases, in the group of OA - in 7 out of 54 samples. KRAS mutation was detected most frequently. The risk of malignancy in OFNs with RAS mutations was 46.2%.
Conclusions

Neither BRAFV600E nor RAS mutations can be recommended as independent markers to detect OCA. The nature of OFN necessitates the search for new reliable molecular genetic markers.