CDKN2A and thyroid gland undifferentiated (anaplastic) carcinoma: Somatic DICER1 and isolated PTEN mutations are primarily associated with benign thyroid nodules, although somatic DICER1 mutations are also seen in different forms of pediatric thyroid carcinoma and in 5–10% of adult follicular thyroid carcinoma.58,59NRAS is the most frequently observed RAS variant and has a 38–65% ROM in ITN.60 The ROM in ITN with an NTRK fusion is >95%.61 In the presence of concurrent mutations, TERT promotor and loss-of-function CDKN2A mutations are associated with aggressive tumor behavior and PTC or anaplastic thyroid carcinoma, respectively.