To elucidate the malignant potential of PDc at the molecular pathological level, this study investigated the type of 53BP1 expression, including the incidence of 53BP1 nuclear foci and NRAS codon 61 and TERT-p mutations in TFTs showing NN appearance with PDc, in comparisons to the other TFTs, including AGs, FAs, minimally invasive follicular carcinomas (MFCs), and widely invasive FCs (WFCs). The gene discussed is TERT; the disease is thyroid gland follicular carcinoma.