(a) Classification of benign thyroid masses; nodular goiter, inflammatory nodules, toxic nodular goiter, thyroid cyst, thyroid adenoma, etc. (b) Malignant thyroid masses Malignant thyroid masses include thyroid cancer, malignant lymphoma of the thyroid, rare metastatic cancer and other primary malignant tumors such as thyroid sarcoma. Treatment principles 1. Multiple nodules (1) If the thyroid function is normal or reduced, a small dose of thyroid hormone treatment can be tried first, if the nodules are more obvious after treatment, surgery should be considered. (2) Toxic thyroid nodules should be surgically removed after hyperthyroidism is controlled. (2) Single nodules (1) Hot nodules: Surgery may be considered for those with hyperthyroidism. (2) Cold nodules: ① Children or young men, especially those with past history of neck radiation therapy or nodules that are hard and immobile, with palpable enlarged lymph nodes in the neck, should be directly treated surgically; ② Newly developed nodules with faster growth rate should be considered for surgical treatment. (3) Female patients with sudden onset of masses larger than 2 cm, single, hard texture and poor mobility should be considered as malignant possibility and should be promptly seen for surgical treatment. Ancillary tests (1) Ultrasound examination of the thyroid gland may show solid, cystic or mixed lesions. (2) The thyroid nucleus scan is divided into “hot nodules” and “cold nodules” according to the ability of the nodules to take up radionuclides. “Hot nodules are almost always benign. “Cold nodules” may be cancerous, but multiple “cold nodules” are mostly benign adenomas or nodules. (3) X-ray examination of the neck Small or sand-like calcifications on the nodules may be the sand bodies of papillary carcinoma. Large, irregular calcifications can be seen in degenerative nodular goiter or thyroid cancer. (4) Thyroid fine needle aspiration cytology This test is simple and safe, and is very helpful in identifying benign and malignant nodules. (5) Determination of thyroid function Functionally autonomous toxic nodules are mostly hyperthyroid, and can be hyperfunctional in the early stages of subacute thyroiditis, while thyroid function in chronic lymphocytic thyroiditis can be normal, hyper or hypothyroid. Most thyroid nodules from the remaining lesions are normal in function.