Introduction: Fine-needle aspiration biopsy (FNAB) is regarded as the gold standard method for the diagnosis of thyroid nodules, but it has its limitations. Additional methods that would improve sensitivity and specificity in the diagnosis of thyroid cancer (TC), especially in indeterminate lesions. Molecular tests seem to be such a tool. BRAF V600E mutation (the most common in TC) can be detected in FNAB and can be potentially a very useful ancillary marker for FNAB practice. The aim of our study was to evaluate the usefulness of the detection of the BRAF V600E mutation in FNAC in the early diagnosis of TC in patients with indeterminate cytology.

Material and method: 2290 FNAB were performed and 147 indeterminate results (group 3, 4, and 5 of the Bethesda system) were obtained. Material from these groups was submitted for molecular tests for the occurrence of BRAF V600E mutation. Sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of the tests were calculated.

Results: Determining the presence of BRAF V600E mutation in FNAC material in groups 3 and 4 together and in group 5 is associated with sensitivity of TC diagnosis of 37.5% and 81.8%, respectively. In all cases the detection of BRAF V600E mutation was associated with histopathologically proving the presence of TC (specificity of the test — 100%).

Conclusions:

1. The presence of BRAF V600E mutation in FNAC material is always associated with the presence of TC.
2. The usefulness of determining the presence of BRAF V600E in FNAC in cytological groups 3 and 4 is associated with low sensitivity in the diagnosis of thyroid cancer.
3. Due to its high specificity BRAF V600E study may be useful in determining the scope of surgery in patients in cytological group 5. (Endokrynol Pol 2016; 67 (1): 41–47)