A thyroid nodule is an isolated lesion within the thyroid gland, either solitary or multiple, that can be palpated and/or ultrasounded to distinguish it from the surrounding thyroid tissue and is the most common type of thyroid disorder. Thyroid nodules are common in the population. The results of a study in the United States that reported the highest prevalence of thyroid nodules applying high-definition ultrasound had a high detection rate of 19 to 67% of thyroid nodules in a randomly selected population, with an average prevalence of 30% to 40% of nodules, including 20.6% to 72% in women and 7.9% to 19.5% in men. The nodule detection rate in autopsy is 8.2% to 65%, with an average of 40% to 50%. If there is a history of radiation exposure to the head and neck at a young age, the average incidence of nodules will be further increased. There is a wide variation in the data reported as to whether the nodules are more solitary than multiple, or more multiple than solitary. Since the incidence of thyroid nodules is so high, proper evaluation of thyroid nodules is particularly important. Among thyroid nodules, benign lesions account for about 95% and malignant lesions account for only about 5% (91% of which are differentiated thyroid cancer, 5% are medullary thyroid carcinoma, only 3% are undifferentiated thyroid carcinoma, and metastatic thyroid carcinoma is extremely rare), and the proportion of benign lesions with symptoms of compression, high-functioning adenoma, and retrosternal goiter, which are absolute indications for surgery, is also small. Therefore, the majority of nodules do not require treatment, so the clinical evaluation is focused on determining the benignity or malignancy of the nodule. Although the development of modern imaging has led clinicians to rely more and more on imaging, history and physical examination are still the most basic steps in assessing the nature of thyroid nodules and should not be ignored. Proper evaluation requires a detailed and complete history taking and careful physical examination of the thyroid gland and adjacent lymph nodes. Factors suggesting a high probability of a malignant thyroid nodule in the history and findings include: 1) a palpable thyroid nodule with a hard texture at age <20 years or >70 years; 2) a history of head, neck or whole body radiation exposure (oncologic radiation therapy or for bone marrow transplantation); 3) a first-degree relative with thyroid cancer; 4) a rapidly growing nodule; 5) hoarseness; 6) vocal cord paralysis; 7) a nodule Ipsilateral cervical lymph nodes are enlarged and fixed. Need to receive further evaluation and management. The literature reports that more than 60% of thyroid cancers can be diagnosed by physical examination by an experienced physician. The only serologic test that should be specific for the diagnosis of malignant nodules is serum calcitonin, which is an indicator for early detection of parathyroid cell hyperplasia and medullary thyroid carcinoma. A blood calcitonin >100 pg/mL without stimulation suggests the possibility of medullary thyroid carcinoma. In contrast, thyroglobulin (Tg), which is elevated in most thyroid diseases, lacks specificity and sensitivity for diagnosing thyroid cancer, and only after total thyroidectomy, the elevation of this index can suggest the possibility of thyroid cancer recurrence. Ultrasound examination is still the most important test for thyroid nodules. It can determine the size and number of nodules and show whether the nodules are cystic or cancerous. The usual signs of cancer include microcalcifications, hypoechogenicity of solid nodules, and an abundant blood supply within the nodule. Echo-free lesions and homogeneous hyperechoic lesions are generally considered to have a low risk of cancer. The disadvantage is that the accuracy depends on the skill and experience of the examiner. In recent years, ultrasonography and ultrasound elastography have been developed to improve the accuracy and reduce the subjectivity of the examiner. Benign nodules are enhanced earlier than the surrounding gland after contrast injection and later than the surrounding gland contouring, and most nodules show peripheral circumferential enhancement, while malignant nodules are mostly hypoechoic with heterogeneous enhancement echogenicity, earlier than Peripheral thyroid tissue fades. The elasticity index scores nodules as 1 to 5 for hardness and 4 to 5 for malignant nodules. The sensitivity, specificity, positive predictive value and negative predictive value of ultrasonography were reported to be more than 90%; the sensitivity, specificity, positive predictive value and negative predictive value of elastography were 88.24%, 91.67%, 88.24% and 91.67%, respectively; the sensitivity, specificity, positive predictive value and negative predictive value of the combined diagnosis were 97.06 The sensitivity, specificity, positive predictive value and negative predictive value of the combined diagnosis were 97.06%, 85.42%, 82.50% and 97.62%, respectively. Although there is controversy over whether to perform puncture biopsy on all suspicious nodules, it is undeniable that the preoperative means to confirm the diagnosis is fine needle aspiration cytology evaluation of thyroid nodules. The 2009 ATA guidelines clearly state that FNA is the most accurate and cost-effective method for preoperative evaluation of thyroid nodules (with a recommended grade of A). The majority of the literature reports that the sensitivity of thyroid FNA ranges from 65% to 98% (median 83%) and the specificity from 72% to 100% (median 92%), and that the deviation between FNA cytology and histopathology is approximately 15%, depending on the skill and experience of the puncture operator and cytopathologist. The management of thyroid nodules based on a graded thyroid FNA diagnosis remains controversial. Most foreign guidelines recommend repeat thyroid FNA for cases that cannot be diagnosed by initial thyroid FNA, with an emphasis on ultrasound-guided FNA, because the diagnosis is clear in 83% of repeat puncture cases, and 8.5% are malignant. However, in the domestic context, it is recommended that when the initial thyroid FNA diagnosis is undiagnostic, it should be combined with ultrasound findings, and surgery is recommended if there are signs of malignancy such as gravelly calcifications, hypoechoic solid nodules, abundant blood flow, unclear borders, and an aspect ratio greater than 1 in the axial view of the nodule. If there are no malignant signs and no clinical symptoms, ultrasound and thyroid FNA can be performed again after 6 to 12 months of follow-up. For micropapillary carcinoma, the “2009 ATA guidelines” clearly state that thyroid nodules ≤0.5 cm may not be evaluated by thyroid FNA even if ultrasonography suggests malignant signs, for reasons related to the good prognosis of micropapillary carcinoma. The 35-year local recurrence rate of micro papillary carcinoma ≤ 0.5 cm was only 3.6%, while the 35-year local recurrence rate of micro papillary carcinoma 0.6-1.0 cm in diameter was only 13.2%, with an overall 20-year survival rate of 99.4%. Whether thyroid FNA will lead to tumor implantation has been a major concern for clinicians and patients, and is one of the causes of controversy. Fine needle puncture with needle sizes between 22G and 27G, corresponding to an internal diameter of 0.7 mm and 0.4 mm, significantly reduces the risk of implantation. In the literature, 288,000 patients underwent thyroid FNA in 1 year in the United States, and as of January 2010, a cumulative total of 19 cases of tumor implantation due to thyroid FNA were reported, and the possibility of tumor implantation due to percutaneous peritoneal FNA has been reported to be 3/100,000 to 9/100,000. Thus, it can be concluded that thyroid FNA is safe. In addition, it is worth stating that in the past, thyroid nuclear imaging was the most commonly used method to assess the nature of thyroid nodules. Radionuclides (131I, 125I, 99mTc) are used for dynamic or static imaging of the thyroid gland to reflect the location, size, morphology and function of the thyroid and its nodules. Thyroid nodules are classified as “hot nodules”, “warm nodules” and “cold nodules” depending on the amount of nuclide taken up by the nodules. However, because most benign nodules, like thyroid cancer, take up less nuclide, they become so-called “cold nodules” and therefore have little diagnostic value. Therefore, thyroid nuclide imaging has diagnostic value only for about 10% of hot nodules (autonomous high-functioning thyroid adenomas), and is of little diagnostic value for the remaining 90% of nodules, and should not be used as a routine test for thyroid nodules.