BRAF mutation analysis and sonography as adjuncts to fine-needle aspiration cytology of papillary thyroid carcinoma: their relationships and roles

Abstract

Objective: The objective of our study was to evaluate the relationships between BRAF mutation status, sonography findings, and fine-needle aspiration cytology features in patients with papillary thyroid carcinoma (PTC) and to evaluate the diagnostic merits of BRAF mutation status and sonography findings as adjuncts to cytologic diagnoses.

Materials and methods: From March 2006 through June 2008, clinicopathologic factors, sonography findings, cytology results, and BRAF mutation status were evaluated in 524 patients (437 women and 87 men) with 553 thyroid nodules; of the 170 malignant nodules, 164 were PTCs. Clinicopathologic factors, sonography findings, and cytology results were correlated with BRAF status. The diagnostic sensitivities and specificities of sonography, cytology, and BRAF analysis and their combinations were compared.

Results: The V600E mutation of BRAF (BRAF(V600E)) was detected in 141 of 170 malignant thyroid nodules (82.9%) (140 PTCs and one follicular variant of PTC). Multiple logistic regression revealed that BRAF status was not associated with sonography features with the exception of a negative relation between BRAF(V600E) and an irregular shape (p = 0.004). An indeterminate cytology result was more frequent for BRAF-negative PTC than BRAF-positive PTC (p = 0.035). By adding BRAF status to cytology, diagnostic sensitivity for PTC was significantly increased (94.1%) as compared with cytology alone (81.8%) (p < 0.001). The triple combination-that is, sonography, cytology, and BRAF analysis-showed higher sensitivity than BRAF plus cytology (98.2% vs 94.1%, respectively) (p < 0.05).

Conclusion: The sonography features of PTC, other than an irregular shape, are not related to BRAF status and the combination of sonography and BRAF testing would increase the diagnostic accuracy of cytologic diagnoses of PTC.