Thyroid tumors are divided into benign tumors and malignant tumors. Benign tumors include thyroid adenoma, thyroid cystadenoma and nodular goiter, which are included in benign thyroid tumors. Malignant tumors include thyroid cancer and some malignant lymphomas. Clinically, malignant tumors mainly refer to thyroid cancer, which has four common types. One is papillary thyroid carcinoma, another is follicular thyroid carcinoma, another is medullary thyroid carcinoma, and another is poorly differentiated or undifferentiated carcinoma. Both benign and malignant are collectively called tumors. However, it is important to distinguish between benign and malignant tumors, which have completely different clinical outcomes, therapeutic effects, and prognoses.