(1) Thyroid adenoma: This disease is mostly seen in young people aged 20 to 30 years old, mostly single nodules with clear borders, smooth surface, slow growth, sudden enlargement often with intracapsular hemorrhage, no cervical lymph node metastasis or distant metastasis. (2) Nodular goiter: Mostly seen in middle-aged women, the lesions can last for years to decades, often involving both sides of the thyroid gland, as multiple nodules, varying in size, and can have cystic changes if the disease has a long course. Carcinoma may occur, and the enlargement of the swelling is obviously accelerated. (3) Subacute thyroiditis: It is often thought to be caused by viral infection and lasts for weeks or months. It is often preceded by a history of whistling tract infection, may be accompanied by mild fever, localized pain that is evident when swallowing and may radiate to the ear, diffuse enlargement of the thyroid gland, or asymmetrical nodule-like swelling, and pressure pain in the swelling. The disease is self-limiting and may resolve spontaneously over a period of several weeks. A small number of patients require surgery to rule out thyroid cancer. (4) Chronic lymphocytic thyroiditis (also known as Hashimoto’s thyroiditis): Chronic progressive bilateral enlargement of the thyroid gland, sometimes indistinguishable from thyroid cancer, usually without conscious symptoms and with elevated autoantibody titers. The disease is sensitive to adrenocorticotropic hormone and sometimes requires surgery and a small amount of x-ray treatment. (5) Fibrous thyroiditis: The thyroid gland is generally enlarged and hard like wood, but often maintains its original shape. It is often fixed to the surrounding tissue and produces symptoms of compression, and is often difficult to distinguish from cancer. It can be surgically explored and the isthmus removed to relieve or prevent compression symptoms.