In the Basis of Hashimoto’s Thyroiditis, to Form Papillary Thyroid Carcinoma, Metastasized and Then to De-Differentiate into Poorly Differentiated Squamous Cell Carcinoma

Abstract

Thyroid squamous cell carcinoma is very rare. At present, it is limited \nto case reports. Since the thyroid follicular epithelium is the non-squamous \nepithelium, how primary squamous cell carcinoma (SCC) of the thyroid occurs is \nstill a controversial issue. Hashimoto’s thyroiditis (HT) is considered to be \nan independent risk factor for thyroid cancer, under the basis of HT, how tumor \ncells evolve and develop to papillary thyroid carcinoma (PTC), and particularly \nto de-differentiate into SCC is elusive. We report a 72-year-old female patient \nwho developed multiple subtypes of PTC on a basis of HT, and finally to \nde-differentiate into SCC within the local foci of lymph node metastasis. We \nfound that there was a variety of sub-types of PTC in this patient in the \nbackground of HT. SCC was found within local lymph node metastasis. \nPathomorphology, immunohistochemistry, and molecular pathology have confirmed \nthat the SCC was derived from PTC, and then developed into poorly \ndifferentiated SCC and/or anaplastic carcinoma. We also conducted a \ncomprehensive literature review.