The thyroid gland is located in the middle of the front of the neck and is shaped like a recluse nail, hence the name thyroid. It moves up and down with the trachea when swallowing. The thyroid gland is surrounded by many important nerves and blood vessels, and damage to the recurrent laryngeal nerve will result in hoarseness. The thyroid gland has many important physiological functions. It secretes the thyroid gland to promote the body’s metabolism, but too much secretion can lead to hyperthyroidism, too little secretion can lead to hypothyroidism, and a lack of it in children can lead to mental retardation. For self-examination of the thyroid gland, use your fingers to press lightly on both sides of the trachea in front of the neck through a mirror and note, first, the shape of the enlarged thyroid gland. Second, note the size of the lump. Third, note the smoothness and softness of the lump. A single nodule that is enlarged but has a smooth and uniform surface may be an adenoma; a single nodule that is enlarged, does not behave smoothly and has a solid feel should be suspected of being a cancer. Fourth, pay attention to the growth rate of the lump. Benign tumors and cysts can last from several months to several years; thyroid cancer lumps grow significantly. Fifth, pay attention to whether lymph nodes can be palpated around the lump. If hard lymph nodes can be palpated in the neck around the thyroid gland, you should seek medical attention quickly. In recent years, the detection rate of thyroid disease has increased significantly. The incidence of thyroid tumors has also increased significantly, with the incidence ranking rising 4 to 5 places compared to 10 years ago and the number of incidences being 4 times higher than 10 years ago. The age of onset of thyroid cancer is mainly young adults between 20 and 40 years old, with more women than men, and the incidence rate is about three times that of men. Symptoms of thyroid cancer: The thyroid gland on the affected side can be palpable nodules with uneven surface, hard texture, no pressure pain and less mobility when swallowing. A thyroid nodule that has existed for many years suddenly and rapidly increases in size, with hard, uneven surface and reduced mobility with swallowing, followed by various compression symptoms, such as dysphagia and obvious Horner’s syndrome, i.e. ipsilateral pupil narrowing, upper eyelid drooping, eye sunken, and ipsilateral head and face without sweating. Ultrasonographic manifestations of thyroid cancer: 1. Number of nodules: Most of them are single, and a few of them are multiple. However, with the application of high-frequency ultrasound, many tiny nodules can be detected, therefore, single or multiple nodules are less and less valuable for judging the benignity and malignancy. 2. Internal hypoechogenicity of nodules: Most of them are hypoechoic and few are isoechoic or hyperechoic. However, internal hypoechogenicity does not mean that the lesion is malignant, because 90% of thyroid nodules can be hypoechoic; in addition, the internal echogenicity of malignant nodules is “uneven” and the posterior echogenicity is diminished or disappears, which can be distinguished from the “uniform hypoechogenicity” of benign nodules. This can be distinguished from the “homogeneous hypoechogenicity” of benign nodules. 3, the longitudinal ratio of the nodule: the longitudinal ratio is close to 1, the peripheral border is unclear, the shape is not regular, or it becomes crab foot-like, and there is no or no complete acoustic halo (dark ring) around the mass, etc. should be considered as malignant possibility. 4. Growth rate of nodules: nodules with faster growth rate (compared with ultrasound at different times) and rapid increase in size within a short period of time should be highly suspected of malignancy after excluding intracapsular hemorrhage. 5, with gravel-like calcification: calcified foci are generally divided into microcalcifications, coarse calcifications, and circular calcifications. At present, scholars at home and abroad generally believe that microcalcifications are the most specific index for diagnosing thyroid cancer, especially for papillary carcinoma, which can reach over 90%. In addition, in young patients (less than 40 years old) and single nodules, the possibility of malignancy increases 4 times if calcification is found. Lymph node metastasis: The ratio of long to short diameter of metastatic lymph nodes in thyroid cancer is mostly less than 1.5, with hypoechoic and some internal echogenicity. 7, color Doppler flow imaging of nodules rich in blood vessels: color Doppler flow imaging of malignant nodules have blood flow or internal linear branching blood flow distribution. In malignant nodules, due to high metabolism and rapid tumor tissue appreciation, the neovascularization lacks smooth muscle and has a thin wall. High-velocity, low-resistance blood flow with peak systolic velocity of 70 cm/s or more is seen. Therefore, if the signal of high-velocity blood flow in thyroid nodules is greater than 70 cm/s, cancer should be considered as a possibility. In addition, thyroid hormone (TSH) should be checked in patients with thyroid nodules. For those with TSH below normal, thyroid ECT (with 99mTcO4 or 123I) should be done to exclude high-functioning thyroid adenomas. The differentiation of benign and malignant thyroid nodules is most important in clinical practice, and fine needle aspiration cytology is an important basis for differentiating benign and malignant thyroid nodules.