Fine-needle biopsy of thyroid nodules and the contribution of molecular analysis of BRAF and RAS mutations.

Background: Thyroid cancer is the most common endocrine malignancy. There is a significant overdiagnosis of thyroid carcinomas that would never clinically manifest, with consequent unnecessary surgical treatment. The fine-needle biopsy and subsequent cytologic examination is of crucial importance in the differential diagnosis of thyroid nodules. On the other hand, a significant portion of the results are indeterminate.

Objective: To assess the relationship of BRAF/RAS mutations in biopsy specimens to histological characteristics of thyroid nodules in individuals who undergone fine-needle biopsy and surgery.

Methods: This cross-sectional study involves 170 subjects with indeterminate cytology analyzed for BRAF/RAS mutations.

Results: Of all 170 patients with indeterminate cytological finding, 103 were indicated for surgery. Of these, 31 were BRAF and 25 RAS positive. Thyroid cancer was diagnosed in 59 patients, while 44 patients had non-malignant thyroid lesions. The BRAF V600E mutation was detected in 30 patients, and the RAS (K-RAS, N-RAS, and H-RAS) mutation in 13 patients with thyroid cancer. In all BRAF-positive nodules, thyroid cancer was histologically confirmed. This means a 100 % positive predictive value of BRAF testing in our study.

Conclusion: Stratification of thyroid lesions with uncertain results of fine-needle cytology using genetic markers can help to deliver more tailored medical treatment (Tab. 6, Ref. 19).