1. Thyroid adenoma: This disease is usually seen in young people aged 20 to 30 years, mostly single nodules, clear borders, smooth surface, slow growth, sudden increase in size, often intracapsular hemorrhage, no cervical lymph node metastases and distant metastases.
2. Nodular goiter: Mostly seen in women over middle age, the disease can last for decades. Multiple nodules on both sides of the lobe are common, varying in size, and may be cystic in nature. Large masses may compress the trachea and displace the trachea, and the patient may have difficulty breathing; the mass may compress the esophagus and cause difficulty swallowing. The probability of carcinoma is low, but it can be seen in elderly patients with large swellings and a long course of disease, which is manifested by a significant acceleration of the swelling’s enlargement.
3. Subacute thyroiditis: It may be caused by viral infection and lasts for several weeks or months. It is often preceded by a history of respiratory tract infection, may be accompanied by mild fever, localized pain, which is obvious when swallowing and may radiate to the ear, diffuse enlargement of the thyroid gland, or asymmetrical nodule-like swelling with pressure pain. It is a self-limiting disease that resolves spontaneously over a period of several weeks. In a few patients, surgery is required to exclude thyroid cancer.
4. Chronic lymphocytic thyroiditis (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 mostly treated conservatively and is sensitive to adrenocorticosteroids, sometimes requiring surgery or a small amount of x-ray radiotherapy.
5. Fibrous thyroiditis: The thyroid gland is generally enlarged and hard like wood, but often retains its original shape. It is often fixed to surrounding tissues and produces symptoms of compression, and is often difficult to distinguish from cancer. When symptoms of tracheal compression appear, the isthmus can be surgically explored and removed.