The thyroid gland is located in the neck below the thyroid cartilage, on both sides of the trachea, and is shaped like a butterfly, like a shield nail, so it is called the thyroid gland. It is the largest endocrine gland in the body, responsible for synthesizing thyroid hormones, regulating the body’s metabolism, and playing an important role in human growth and development. “When thyroid hormones are produced in excess, the body’s metabolism is accelerated and symptoms such as rapid breathing and heartbeat and profuse sweating occur, called hyperthyroidism; conversely, when its supply is insufficient, the body’s metabolism slows down and symptoms such as coldness, drowsiness and rough skin occur, called hypothyroidism or hypothyroidism. In fact, the human thyroid gland is originally homogeneous in texture, but for various reasons one or more abnormal masses of tissue structure appear in the thyroid gland. This is often referred to as a thyroid nodule. The prevalence of thyroid nodules in the general population is 3-7% on palpation and 20-70% on ultrasound. The vast majority of thyroid nodules are benign, with malignancy accounting for only 5%. Depending on the etiology, they are divided into: hyperplastic nodular goiter, neoplastic nodules: benign tumors, malignant tumors, cysts, and inflammatory nodules. The key to diagnosis is to identify the benign and malignant nature of the nodules. Most of them are clinically asymptomatic, but are found on physical examination or ultrasonography; very few have local pressure manifestations; a few have abnormal thyroid function, hyperthyroidism or hypothyroidism manifestations. Clinical clues suggesting the possibility of malignant lesions: history of treatment with neck radiography; history of medullary thyroid cancer or family history; age less than 20 years or more than 70 years . Males; nodules that increase significantly in size over a short period of time, with symptoms of local compression, including persistent hoarseness, dysphonia, dysphagia, and dyspnea; nodules that are hard, irregularly shaped, and fixed, with enlarged lymph nodes in the neck. All patients with thyroid nodules should have their serum TSH and thyroid hormone levels measured. 3. The majority of patients with malignant nodules have normal thyroid function. 4. If the serum TSH is lower than normal and the nuclear imaging suggests a high-functioning nodule, the nodule is almost always benign. High definition thyroid ultrasonography is the most sensitive test for evaluating thyroid nodules. It can be used not only to identify the nature of the nodule, but also to localize, puncture, treat and follow up on the thyroid nodule under ultrasound guidance. This test is required for all patients suspected of having a thyroid nodule or who already have a thyroid nodule. The report should include the location, morphology, size, number of nodules, nodule margins, internal structure, echogenic features, blood flow and cervical lymph nodes. Thyroid nuclide imaging is the only imaging method that can evaluate the functional status of the nodules. Nodules can be classified as “hot nodules”, “warm nodules” and “cold nodules” according to their ability to take up radionuclides. The percentage of “hot nodules” is 10% and the percentage of “cold nodules” is 80%. The rate of malignancy in “cold nodules” is 5-8%. Therefore, the use of “cold nodules” to determine the benignity or malignancy of thyroid nodules is not very helpful. MRI and CT are less sensitive than thyroid ultrasound in detecting thyroid nodules and determining the nature of nodules, and they are expensive. Therefore, they are not recommended for routine use. However, the relationship between the thyroid nodule and the surrounding tissues should be evaluated when surgery is required, and it has particular diagnostic value especially for the detection of retrosternal goiter. Fine needle aspiration cytology biopsy (FNAC) of the thyroid is the most reliable and valuable diagnostic method to identify benign and malignant nodules. FNAC can be used to identify the cytologic type of the cancer before surgery and can help determine the surgical plan. It is worth noting that FNAC cannot distinguish follicular carcinoma from follicular cell adenoma. Moreover, the diagnosis has some limitations and is related to the surgeon’s experience. Treatment of thyroid nodules 1. The choice of treatment should depend on the characteristics of thyroid ultrasonography and the results of FNAC. 2. Treatment of malignant thyroid nodules 3. Surgery is the first choice for most malignant thyroid tumors. 4.Undifferentiated thyroid cancer is highly malignant and almost all of them have distant metastasis at the time of diagnosis, so it is difficult to achieve the treatment purpose by surgery alone. 5.Thyroid lymphoma is sensitive to chemotherapy and radiotherapy, once diagnosed, chemotherapy or radiotherapy should be used. Most of thyroid cancers can be treated very well and it can be said that thyroid cancer is a “curable” disease at present. Of course, some herbal treatments can be tried. 2. Follow up is required, every 6 months to 12 months. 3.Thyroid ultrasonography, repeat FNAC if necessary. 4.Only a small number of patients need surgery, medication (thyroid hormone suppression therapy) and PEI (ultrasound-guided percutaneous alcohol injection) radioactive 131 iodine treatment Treatment of suspected malignant and undiagnosed thyroid nodules Cystic or solid thyroid nodules that cannot be clearly diagnosed by FNAC examination should be repeated FNAC examination. If the diagnosis is still not confirmed by repeated FNAC examination, especially if the nodule is large and fixed, surgical treatment is required. In conclusion, when a thyroid nodule is found, first of all, do not be overly nervous. If necessary, a consultation with a thyroid surgeon and nuclear medicine physician should be requested, and reasonable treatment or observation and follow-up should be provided.