NTRK1 rearrangements have been shown to be involved in thyroid carcinogenesis. Several studies show that NTRK1 rearrangements may be associated with a worse clinical course when compared with NTRK1 rearrangement-negative Papillary Thyroid Carcinomas. The treatment of patients with NTRK fusion-positive cancers with a NTRK inhibitor, such as the FDA approved drugs Larotrectinib or Entrectinib, is associated with high response rates regardless of NTRK gene, fusion partner, and tumor type. Hence, detection of NTRK1 rearrange-ments by in situ Hybridization may be of prognostic and therapeutic significance.