SRC and congenital hypothyroidism: In this case, thyroglobulin and TTF-1, which are the thyroid reliable origin markers [10, 15, 19, 20], were identified by immunohistochemistry in the HFCs, and there were no capsule, the follicular hyperplasia was diffuse, some HFCs showed SRC differentiation in combination with the low tumor atypia (as evidenced by the limited growth of tumor cells, lack of obvious mitosis and blood vessel invasion, and absence of tumor-like cells in other organs), resulting in the comprehensive diagnosis of congenital goiter with areas of SRC differentiation.