The mean frequencies of TERT promoter mutations in PTC, conventional FTC, Hürthle cell carcinoma, poorly differentiated carcinoma and anaplastic carcinoma were 11.3 % (95 % CI 9.3–13.5), 21.3 % (95 % CI 14.2–29.4), 6.7 % (95 % CI 0.2–21.4), 39.6 % (95 % CI 31.3–48.2), and 38.5 % (95 % CI 32.6–44.7), respectively (Figs. 3 and 4). This evidence concerns the gene TERT and undifferentiated carcinoma.