Telomerase reverse transcriptase promoter mutations are found in subsets of follicular thyroid carcinomas and follicular tumors of uncertain malignant potential while exceedingly rare in recurrence-free follicular thyroid adenomas.
We investigated the prevalence and clinical impact of mutations of BRAF, 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), Hürthle cell adenoma (n = 54), noninvasive follicular thyroid neoplasms with papillary-like nuclear features (n = 50), follicular thyroid carcinoma (n = 40), Hürthle cell carcinoma (n = 10), and poorly differentiated thyroid carcinoma arising in a well-differentiated follicular neoplasm (n = 7), and 120 classic papillary carcinoma.
Lately, recurrent mutations in the promoter of the Telomerase reverse transcriptase (TERT) gene have been coupled to FTCs, whereas FTAs usually lack this aberrancy.
TERTC228T is far more common than TERT C250T and their collective prevalence is, on average, 0, 11.3, 17.1, 43.2 and 40.1% in benign thyroid tumors, papillary thyroid cancer (PTC), follicular thyroid cancer, poorly differentiated thyroid cancer and anaplastic thyroid cancer, respectively, displaying an association with aggressive types of thyroid cancer.
Nine of the 52 FTCs (17%) exhibited the TERT mutation (8 of 9 C228T and 1 of 9 C250T), and the presence of the mutation was associated with shorter patient survival.
All 10 slides in which no RT-PCR products were noted were older than 3 years. hTERT gene expression was demonstrated in FNAs from two of seven cases (29%) of hyperplastic nodule, one of one case (100%) of Hashimoto's thyroiditis, three of eight cases (38%) of follicular adenoma, three of eight cases (38%) of Hürthle cell adenoma, three of four cases (75%) of follicular carcinoma, two of two cases (100%) of Hürthle cell carcinoma, and 11 of 18 cases (61%) of papillary carcinoma.