According to statistical analysis, thyroid nodules can be detected by high-resolution ultrasound in more than 60% of the population. In the face of such a high incidence, it is important to understand the true nature of thyroid nodules. A nodule is a lump of unknown nature. Broadly speaking, thyroid nodules can be divided into the following categories: nodular goiter formed by proliferation and degeneration; autonomously functioning nodules, such as high-functioning adenomas, toxic nodular goiters and previous plummer’s disease, which often do not follow instructions and secrete thyroid hormones on their own, leading to hyperthyroidism; neoplastic nodules, including adenomas and thyroid cancer; cystic changes, which can be combined with Cystic changes, which can be combined with nodular goiter or thyroid cancer; and inflammatory nodules, including subacute thyroiditis and autoimmune thyroiditis. Thyroid nodules occur in both men and women, young and old, high and low, and of different ethnicities. Common causes are often environmental pollution, radiation exposure, iodine deficiency or excess, and genetics. Among thyroid nodules, malignant neoplasms of the thyroid gland are particularly important. The histologic types of thyroid cancer include papillary thyroid carcinoma (PTC), follicular thyroid carcinoma (FTC), and anaplastic thyroid cancer (ATC), which originates from the follicular epithelium of the thyroid gland. ATC). The main molecular pathogenesis of medullary thyroid carcinoma (MTC), which originates from parafollicular C cells, is the abnormal activation of RET signaling caused by mutations in the RET gene. Among them, PTC and FTC are traditionally defined as differentiated thyroid carcinoma, and papillary thyroid carcinoma and follicular carcinoma as differentiated carcinoma account for more than 90% of the incidence of thyroid cancer. Differentiated thyroid cancer tends to be inert and is usually curable. Undifferentiated thyroid cancer is rare and has a very high mortality rate. Ultrasonography is currently the imaging method of choice for diagnosing thyroid disorders and has the advantages of being easy, reproducible, noninvasive, quick, free of ionizing radiation, and inexpensive. Ultrasound and color Doppler ultrasonography allow measurement of thyroid volume, size of nodules, presence of calcification, texture (cystic solidity), structure (diffuse, single or multiple), borders, and echogenic characteristics (hyperechoic, isoechoic and hypoechoic). The size and structural characteristics of the lymph nodes in the neck can also be evaluated. The following signs are usually seen on ultrasound imaging of thyroid cancer: 1) hypoechoic substantial nodules; 2) abundant blood flow signal inside the nodules (in case of normal TSH); 3) irregular nodule morphology and halo absence; 4) microcalcifications, pinpoint diffuse distribution or clusters of calcifications inside the nodules; 5) abnormal ultrasound images of cervical lymph nodes, such as irregular border, round shape, internal If three of the above six items are present in the ultrasound image, thyroid cancer is very likely. Nowadays, with the improvement of ultrasound technology, it is possible to detect the hardness of the nodule by elastic ultrasound to distinguish the benignity and malignancy of thyroid nodules from another visual perspective. The above figure shows the ultrasound images of malignant thyroid tumors collected by me in my clinical work. The above image is an ultrasound image of medullary thyroid carcinoma. The image on the right side is atypical and the diagnosis was confirmed by postoperative paraffin pathology and molecular immunopathology. The image above shows the hardness of a thyroid nodule using real-time elastic ultrasound technology, which guides the determination of the benignity or malignancy of the nodule. This image shows postoperative pathology of papillary thyroid carcinoma. The image above shows a nodular goiter. There is a “love heart” on Pluto and a “love heart” on the thyroid gland. The above picture shows an inflammatory nodule, which varies in size and most do not require surgery. The definition of the nature of thyroid nodules, especially the determination of the benignity and malignancy of neoplastic nodules, is a major clinical challenge. Every year, many patients with thyroid nodules are screened by thyroid ultrasound, but how to identify the patients who really need thyroid surgery in this sea of people needs to be judged by specialized doctors.