Parathyroid cysts are benign tumors and are very rare clinically. Clinical manifestations: The disease is more common in women, with a male to female ratio of about 1:2~3.5, and the age of onset is mostly between 30~60 years old. It is usually manifested as a neck mass, often single, occasionally multiple. The masses can be found up to the angle of the jaw and down to the mediastinum, but are mostly located in the lower part of the neck, at the lower pole of the thyroid gland, and a few cysts can develop forward and grow completely into the thyroid tissue. The swelling can be palpated with different sizes, clear borders, smooth surface, soft and elastic texture or hard and tense texture, no pressure pain, and can mostly move with swallowing. Usually there is no local symptom, and when the cyst increases to a certain degree, local discomfort, pain, dysphagia, dyspnea, hoarseness, choking and other symptoms may appear. In addition to local symptoms, functional cysts may also show symptoms and signs of hyperparathyroidism, such as high blood calcium and low blood phosphorus, and early symptoms include muscle weakness, loss of appetite, nausea, polyuria, lumbar pain, and hematuria; in late stage, patients may have generalized skeletal pain, spontaneous fractures, multiple kidney stones, hypertension, and renal insufficiency. The course of the disease varies from several years to more than 10 years. Diagnosis: Because parathyroid cysts themselves have no specific symptoms and signs, the rate of clinical misdiagnosis is extremely high and they are often diagnosed as thyroid adenomas or cysts. 1. Ultrasound of the neck: non-specific, often reported as a cystic occupying lesion of the thyroid. However, if a homogeneous dark area of fluid is seen below the thyroid gland with an intact thin envelope that pushes the thyroid gland upward and displaces it, a parathyroid cyst should be considered. 2.Isotope scan and CT examination of the neck: as diagnostic imaging methods for parathyroid gland diseases, they have very specific diagnostic value for tumor localization and are easy to diagnose functional cysts in combination with clinical practice, while preoperative diagnosis of non-functional cysts is more difficult. 3.needle aspiration cytology examination: if clear, thin and colorless liquid is aspirated, it is highly suggestive of parathyroid cyst. If the fluid is cloudy, coffee-colored or bloody, it is suggestive of a thyroid cyst. The diagnosis of the disease can be confirmed by aspiration of fluid with elevated PTH or parathyroid cells, and the presence or absence of hypercalcemia, blood PTH levels and patient signs can determine the function of the cyst. Treatment: Once a parathyroid cyst is clearly diagnosed, surgery should be the main treatment. Since parathyroid cysts have an intact envelope, they are easy to remove surgically. Surgical excision is the only effective approach for functional cases. There is no consensus on the treatment of non-functional cases. One opinion is that the disease has not been found to have a malignant tendency, so puncture aspiration or injection of sclerosing agent after puncture aspiration can be preferred and this method is often curative. In case of short-term recurrence after treatment, or if the cyst extends into the mediastinum, or if there are symptoms of compression, or if other tumors cannot be excluded, surgery should be performed. Another opinion is that puncture aspiration changes the morphology and tension of the cyst, which is not conducive to complete surgical resection; on the other hand, puncture aspiration may cause parathyroid cells or tissue implantation in the cyst wall or spillage of cystic fluid, causing recurrence. Therefore, complete surgical resection is advocated.