Thyroid adenoma cystic degeneration is a secondary change of thyroid adenoma that produces a fluid cyst on top of the thyroid adenoma. It is a liquid cyst formed due to the rupture and bleeding of blood vessels within the wall of the thyroid adenoma capsule, or due to necrosis and liquefaction of the thyroid tumor caused by insufficient blood supply. Thyroid adenoma usually develops slowly, most patients have no obvious symptoms in the early stage, usually found during physical examination, the surface of the nodule is smooth, there is no pressure and pain, and it moves up and down with swallowing movements. When cystic degeneration occurs the tumor increases in size, and pressure symptoms such as difficulty in swallowing, choking on drinking water, hoarseness and dyspnea may occur. Once thyroid adenoma cystic degeneration develops pressure symptoms, surgical removal of the thyroid mass is necessary, and after surgery, levothyroxine sodium tablets and other medications are needed to prevent hypothyroidism. Thyroid adenoma cystic degeneration is mainly diagnosed and identified by ultrasound, it is recommended to go to the regular hospital for examination and clear diagnosis.