NTRK1 and thyroid gland undifferentiated (anaplastic) carcinoma: The genetic alteration of serine/threonine-protein kinase B-Raf (BRAF)V600E, Neurotrophic Receptor Tyrosine Kinase 1 (NTRK1), rearranged during transfection (RET), and the three isoforms of RAS (N, H, and K) occurs in anaplastic thyroid carcinoma (ATC) with aggressive metastasis to the lungs, bones, and regional lymph nodes.