The thyroid gland is located in the lower part of the front of the neck and is shaped like an H. It is divided into two lobes, the right and left lobes, which are connected in the center by an isthmus across the front of the trachea. The two lobes are attached to the lower larynx and upper trachea on both sides and can move up and down with swallowing. When the thyroid gland is significantly enlarged, the skin of the lower anterior neck can be seen to bulge. The thyroid lobes reach upward to the upper edge of the larynx and downward to the sixth ring of the trachea, and are usually about 4-5 centimeters long and 2 centimeters wide. The isthmus is located in front of the 2nd-4th tracheal rings, and sometimes a cone-shaped lobe extends upward from the isthmus, varying in length. The adult thyroid gland weighs about 20-30 grams. The location of the thyroid gland is closely related to the parathyroid glands, laryngeal nerves and esophagus, and other structures. During thyroid surgery, these tissues and organs can be damaged, and the corresponding symptoms appear: hypocalcemic convulsions, hoarseness, and dysphagia. The hormones secreted by the thyroid gland are mainly T3 and T4, which are used to regulate basic physiological processes such as metabolism, growth and development. Excessive secretion of hormones causes hyperthyroidism, which can be characterized by panic attacks, excessive sweating, weight loss and protruding eyeballs; insufficient secretion of hormones can be manifested as hypothyroidism: lethargy, skin roughness, hair loss and mucous oedema, etc. Cretinism can also be seen in children. Classification of goiter There are many types of thyroid disorders, and the current classification of thyroid disorders is inconsistent. In terms of thyroid swelling, it can be divided into thyroid non-neoplastic swelling and thyroid neoplastic swelling, the former is also known as tumor-like disease, mainly refers to nodular goiter, in addition, it can also include chronic lymphocytic thyroid, and chronic fibrous thyroiditis and hyperthyroidism, etc.; the latter includes benign adenomas of the thyroid gland and malignant thyroid cancer. The latter includes benign thyroid adenomas and malignant thyroid carcinomas. Thyroid carcinomas include papillary adenocarcinoma, follicular adenocarcinoma, medullary adenocarcinoma and undifferentiated carcinoma of the thyroid. Papillary thyroid adenocarcinoma and follicular thyroid adenocarcinoma, also known as differentiated thyroid cancer, account for more than 90% of all thyroid cancers, and have a very high cure rate, with a 10-year survival rate of more than 90%, which makes them one of the best prognoses of malignant tumors in human beings. However, intriguingly, undifferentiated thyroid cancer has a very poor prognosis, with most patients dying within 1 year, and the 5-year survival rate is only about 10%, which is one of the worst prognoses among human malignant tumors. The prognosis of medullary thyroid carcinoma is intermediate between differentiated thyroid carcinoma and undifferentiated carcinoma. Diagnosis of Thyroid Goiter Patients with thyroid goiter usually have no conscious symptoms. Most patients see a localized bulge in the front of the neck by looking in the mirror or by others by chance, or touch a lump in the neck unintentionally by themselves, while many other patients find thyroid goiter by physical examination. A few thyroid cancer patients come to the doctor with hoarseness or metastatic cancerous mass in the lymph nodes of the neck. Thyroid function tests, ultrasound, isotope scanning, CT, MRI and fine needle aspiration biopsy are the commonly used diagnostic tools for thyroid goiter. Thyroid ultrasound is considered to be a simple, fast and effective examination method, but its diagnostic accuracy is directly related to the experience of the ultrasound doctor. Fine-needle aspiration biopsy can be used to definitively diagnose the nature of the thyroid mass preoperatively. Because the rate of cervical lymph node metastasis in differentiated thyroid cancer is as high as 30-50%, the presence of cervical lymph node metastasis should also be taken into account when diagnosing thyroid cancer. Surgical treatment of benign thyroid goiter Clinically, the treatment of benign thyroid goiter has been controversial. Surgery is the mainstay of treatment for benign goiters, and the surgical approaches include thyroid goiter removal, partial thyroidectomy, lobectomy of one side of the gland, subtotal thyroidectomy and total thyroidectomy. For benign lesions, normal thyroid tissue should be preserved as much as possible, and total thyroidectomy is generally avoided to minimize the complications of surgery. Common complications include recurrent laryngeal nerve injury, hypothyroidism, hypocalcemic convulsions, and esophageal and tracheal injuries. Non-neoplastic thyroid masses such as nodular goiter, chronic lymphocytic thyroid, chronic fibrous thyroiditis with hyperthyroidism are not necessarily indications for surgery. Simple goiter is a compensatory enlargement of the thyroid gland due to iodine deficiency, goitrogenic substances, or enzyme deficiencies, and is usually not associated with altered thyroid function. When compensatory enlargement of the thyroid gland is combined with nodule formation, it is called nodular goiter. Indications for surgery: 1. The lesion causes compression of the surrounding trachea and esophagus; 2. Malignant lesions are suspected. Thyroid adenomas are common benign thyroid tumors, which can be classified into simple adenomas, embryonal adenomas, fetal adenomas, eosinophilic adenomas and toxic adenomas according to the microscopic structure and function of the tumor. Thyroid adenomas are an indication for surgery, and about 10% of thyroid adenomas develop malignancy. If a thyroid adenoma is diagnosed, thyroidectomy should be performed without excessive removal of normal thyroid tissue.