The thyroid gland, located in front of the neck and shaped like a butterfly, is an important endocrine organ in the body. It secretes thyroid hormones (T3 and T4) to control the body’s development and metabolic balance. A “thyroid nodule” means a lump in the thyroid gland that is only a few millimeters in size in the early stages, but a significant number of them are found during a medical ultrasound, and some of them are already malignant, especially in young patients. How to deal with thyroid nodules? Should they be kept under observation or surgically removed (i.e., the “stay or go” question)? Generally speaking, thyroid nodules generally do not require surgery, but should be kept under observation or treated with medication and reviewed regularly. Surgery should only be considered for suspected malignancy, hyperfunction, or aesthetic concerns …… The medical definition of thyroid nodules: confined masses in the thyroid tissue, cystic, solid and cystic, benign and malignant, may appear as single or multiple nodules, and are common lesions of the endocrine system. Especially in recent years, the prevalence of thyroid nodules has increased significantly, and most patients have no obvious symptoms themselves. Only a small percentage of patients present to the hospital with difficulty in breathing, swallowing, hoarseness, discomfort such as pain or swelling in the neck, and enlarged lymph nodes. Studies have reported that the incidence of palpable thyroid nodules is generally 4% to 7%, while the rate of positive thyroid nodules detected by ultrasound is as high as 16% to 67%, and the incidence is two times higher in women than in men, so that most thyroid nodules are found accidentally. How exactly do thyroid nodules occur? In fact, the causes are related to a number of factors, so there is no need to get hung up on which factor is relevant to an individual. In summary, the risk factors include genetics, gender, age, iodine diet, autoimmunity, history of radiation exposure (ionizing radiation), environmental pollution, infectious factors, etc. The occurrence of thyroid nodules is often the result of a combination of factors. The survey on thyroid nodules in China shows that the total detection rate of thyroid nodules is 42.44%, 36.83% and 48.68% for men and women respectively, which is higher than that of men. Among all thyroid tumors, the elderly tend to account for a larger proportion of patients, but patients with thyroid cancer, especially papillary thyroid carcinoma, are relatively young, with women aged 21-40 being the most common among adults with papillary thyroid cancer. The rate of thyroid cancer in adolescents with thyroid nodules is higher than in adults. What tests are needed to detect thyroid nodules? Usually, thyroid tests include thyroid function measurement, color ultrasound, ultrasonography, ultrasound-guided fine-needle aspiration cytology and histology, CT, isotope scan, etc., to help determine the nature and functional status of thyroid nodules and provide a basis for further treatment. Ultrasound of the thyroid gland, as the first choice for thyroid disease examination, contributes to the determination of the nature of the nodule, not only by observing the tiny foci of 2-3 mm in the thyroid gland, but also by clearly showing the internal conditions of the nodule – the presence of small structures such as borders, envelopes, calcifications, and changes in blood flow and frequency spectrum. Ultrasound-guided fine-needle aspiration cytology is more accurate in diagnosing the nature of nodules. As a new internationally recognized method for qualitative diagnosis of thyroid nodules, it uses high-frequency ultrasound to monitor the needle approach and perform three to five repeated aspirations within the nodule, and the cells carried during the needle aspiration are diagnosed cytologically, which has the advantages of easy operation, accurate results, and few complications. At the same time, safe and non-invasive ultrasonography is also a good way to examine thyroid nodules and is now increasingly used in the diagnosis of thyroid diseases. Ultrasonography is used to determine the vascular and microvascular status of tissues and tumors for nodules that are not clearly diagnosed by conventional ultrasound, and to identify their benign and malignant nature by using contrast enhancement, especially the positive diagnosis rate of microscopic thyroid cancer less than 1 cm is significantly increased. Since there are benign and malignant thyroid nodules, how is the medical classification? Benign nodules mainly include nodular goiter, thyroid adenoma, inflammatory nodule, thyroid cyst, high-functioning adenoma, etc. Malignant nodules are mainly thyroid cancer, which is classified into papillary carcinoma, follicular carcinoma, medullary carcinoma and undifferentiated carcinoma according to the histological pattern. Do all thyroid nodules need surgery? The answer is no. Usually, thyroid nodules will only show symptoms when they compress or invade the surrounding tissues, such as difficulty in breathing due to compression of the trachea, difficulty in swallowing due to compression of the esophagus, and hoarseness due to invasion of the recurrent laryngeal nerve, while thyroid nodules located inside the gland that are not huge, even if they are malignant, usually have no obvious manifestations. However, the absence of symptoms does not mean that there is no possibility of malignancy. The nature of the nodule must be evaluated comprehensively and appropriate treatment must be taken. For most patients with benign nodules, there is no need to be overly nervous, but attention should be paid to regular follow-up review. Generally speaking, thyroid ultrasound and serum thyroid function index should be reviewed every 3-6 months to prevent the development and changes of the disease and missed treatment time. If the following conditions occur during the review, surgery should be performed: 1. cancer is considered; 2. tracheal or esophageal compression symptoms occur; 3. hyperthyroidism is combined; 4. retrosternal goiter; 5. the appearance is seriously affected; 6. the patient’s mind is so burdened that it affects normal life. For those with high suspicion of malignancy in the preoperative examination, or those with definite malignancy in the pathological diagnosis, surgery should be performed decisively, and postoperative levothyroxine tablets should be taken to supplement replacement therapy and regular review, and some lymph node metastases should be treated with radioactive iodine. Because the most common type of thyroid cancer is papillary cancer, commonly known as inert cancer, the survival rate of this type of thyroid cancer after surgery is very high and most patients can live like normal people. To sum up, the incidence of thyroid nodules is significantly higher today and attention should be paid to regular medical checkups to detect thyroid lesions. Once a thyroid nodule is found, there is no need to panic, but you should go to a hospital specialist to further examine the condition of the nodule. A good portion of them can be observed and followed up, but some of them have to be treated surgically, especially for early malignant thyroid nodules early surgery, lifelong cure and excellent prognosis!