Malignant thyroid tumors, including thyroid cancer, thyroid malignant lymphoma and metastatic thyroid cancer, are very rare. Most malignant tumors refer to thyroid cancer, which is divided into four types, as follows: 1. papillary thyroid cancer: it occurs in young and middle-aged women, and accounts for about 70% of thyroid cancer; 2. follicular thyroid cancer: it accounts for about 10%-15% of thyroid cancer, and occurs in middle-aged women; 3. undifferentiated thyroid cancer; undifferentiated cancer has a bad name, and accounts for 5%-10% of thyroid cancer. The malignant degree is very high; 4. Medullary thyroid carcinoma: It has the tendency of family gathering and hereditary tendency, and the malignant degree is higher than papillary thyroid carcinoma and follicular carcinoma, but not as powerful as medullary carcinoma. The causes of malignant thyroid tumors are not clear, but research now suggests that they are related to oncogenes, ionizing radiation, iodine deficiency, endocrine status, estrogen and genetic predisposition.