Recent studies have indicated a wide expression of Shh pathway components such as Ptch and Smo receptors and the transcription factor Gli1 in PTC papillary thyroid carcinoma (PTC), ATC and in benign follicular thyroid adenoma (FTA) suggesting that the Shh pathway activation occurs at an early phase of thyroid tumor development. This evidence concerns the gene SHH and thyroid gland papillary carcinoma.