[Multi-gene mutations in ultrasound-guided fine-needle aspiration specimens of thyroid micronodules and diagnostic value in thyroid microcarcinomas using next-generation sequencing].

Objective: To explore the detection of BRAF, RAS, TERT promoter, and TP53 gene mutations in solitary thyroid micronodule (TMN) specimens obtained by ultrasound-guided fine-needle aspiration (US-FNA) using next-generation sequencing (NGS) technology and assess its diagnostic value in thyroid microcarcinomas (TMC). Methods: On-site recruitment of 428 patients with single suspicious TMC who underwent thyroid ultrasound examination, US-FNA, and NGS from September 2018 to July 2021 at Beijing Tongren Hospital affiliated to Capital Medical University. A total of 147 patients were finally included. NGS was used to detect mutations in the BRAF, RAS, TERT promoter, and TP53 genes in the US-FNA specimens. Comparisons were made between patients with and without gene mutations in terms of age, gender, and the maximum diameter of nodules. The diagnostic efficiency of BRAF mutation for TMC was calculated using the receiver operating characteristic (ROC) curve, with postoperative pathology as the gold standard. Results: The age [M (Q₁, Q₃)] of the 147 patients was 43.0 (32.0, 51.0) years, and 37 were male (25.2%). Among the 147 US-FNA specimens, 97 (66.0%) were detected with BRAF gene mutations, all of which were p.V600E point mutation; 6 (4.1%) were detected with RAS gene mutation, and no TERT promoter or TP53 gene mutations were detected. Postoperative pathology confirmed that 136 cases were TMC, all of which were papillary thyroid microcarcinomas (PTMC); 11 cases (7.5%)were benign. Among 136 TMC samples, BRAF gene mutations were detected in 97 cases (71.3%). There were no statistically significant differences in age, gender, and maximum nodule diameter between patients with and without BRAF gene mutations (all P>0.05). The sensitivity and specificity of BRAF gene mutation in diagnosing TMC were 71.3% and 100.0%, respectively, with an area under the ROC curve (AUC) (95%CI) of 0.857 (0.789-0.925). For nodules classified as Bethesda Ⅲ-Ⅴ, the sensitivity and specificity were 63.0% and 100.0%, respectively, with an AUC (95%CI) of 0.815 (0.680-0.950). Conclusions: NGS technology can successfully detect multiple gene mutations in US-FNA specimens from TMN patients, especially BRAF gene mutation, and BRAF gene mutation has certain value in diagnosing TMC.