Analysis of RAS mutation and PAX8/PPAR gamma rearrangements in follicular-derived thyroid neoplasms in a Korean population: frequency and ultrasound findings

Abstract

Objective To investigate the frequency and ultrasonography (US) findings of RAS mutations and PAX8/PPAR gamma rearrangements between follicular thyroid adenomas (FTAs) and follicular thyroid carcinomas (FTCs) in a Korean population. Methods RAS mutations and PAX8/PPAR gamma rearrangements in 56 FTAs and 35 FTCs were analyzed. We also analyzed the US findings of FTCs and FTAs. Results 16 nodules of 35 FTCs (45.7 %) and 19 nodules of 56 FTAs (33.9 %) harbored RAS mutations. Three FTCs and three FTAs showed two point mutations simultaneously. K-RAS codon 12-13 (n = 6, 31.6 %), N-RAS codon 61 (n = 5, 26.3 %), H-RAS codon 61 (n = 4, 21.1 %), K-RAS codon 61 (n = 3, 15.8 %), and N-RAS codon 12-13 (n = 1, 5.3 %) were found in FTCs, and N-RAS codon 61 (n = 10, 45 %), K-RAS codon 12-13 (n = 5, 22.7 %), H-RAS codon 61 (n = 5, 22.7 %), K-RAS codon 61 (n = 1, 4.5 %), and N-RAS codon 12-13 (n = 1, 4.5 %) were observed in FTAs. 4 of 56 (7.1 %) FTAs and 1 of 35 (2.9 %) FTCs represented PAX8/PPAR gamma rearrangements, respectively (P = 0.645). The absence of a hypoechoic rim (P = 0.021) and presence of calcifications (P = 0.049) were significantly associated with FTCs compared with FTAs. Conclusions RAS mutation frequency targeting the Korean population showed a 45.7 % in FTCs and 35.7 % in FTAs, and PAX8/PPAR gamma rearrangements were more frequently showed in FTAs. K-RAS codon 12-13 was the most common RAS mutation in FTCs, whereas N-RAS codon 61 was more frequent in FTAs. The presence of calcifications and absence of a hypoechoic rim showed more frequently in FTCs.