Clinical utility of EZH1 mutations in the diagnosis A Check for of follicular-patterned thyroid tumors

Follicular-patterned tumors of the thyroid gland are characterized by a predominantly follicular growth pattern. They frequently harbor RAS mutations, not BRAF mutations. Technological advances in molecular testing have discovered novel RAS-type mutations. However, clinical significance of these mutations remains unknown. We investigated the prevalence and clinical impact of mutations ofBRAF, NRAS, HRAS, KRAS, EZH1, EIF1AX, and TERT genes by Sanger sequencing in a series of 201 follicular-patterned thyroid tumors including follicular adenoma (n = 40), Hfirthle cell adenoma (n = 54), noninvasive follicular thyroid neoplasms with papillary-like nuclear features (n = 50), follicular thyroid carcinoma (n = 40), Hiirthle cell carcinoma (n = 10), and poorly differentiated thyroid carcinoma arising in a well-differentiated follicular neoplasm (n = 7), and 120 classic papillary carcinoma. Two hotspots of EZH I mutations were only found in RAS-negative follicular-patterned tumors. EZH1 mutations were detected in 3% of follicular adenoma and in 20% of Hfirthle cell adenoma, and one minimally invasive Hiirthle cell carcinoma. Thyroid tumors with EZH1 mutations reported in the literature were benign in most cases. Otherwise, they were minimally invasive or noninvasive cancer. EIF1AX mutation was found in one follicular adenoma. We confirmed the presence of RAS mutations and BRAF K601E mutation in benign, borderline, and malignant follicular-pattemed tumors. No BRAF V600E was found in all follicular-pattemed tumors. This study also confirmed the occurrence of TERT promoter mutations in high-risk thyroid cancers. These genetic markers can be used for the diagnostic purpose and risk stratification of thyroid nodules. (C) 2018 The Authors. Published by Elsevier Inc.