Microcysts of the parathyroid gland are a common occurrence in the general population, but macroscopic parathyroid cysts of the neck are rare clinical entities. We report two cases of parathyroid cyst that extended to the mediastinum. Parathyroid cysts are classified as nonfunctional and functional. We discuss the clinical features of nonfunctioning and functioning parathyroid cyst. Fine needle aspiration biopsy with ultrasonography is a very useful technique for diagnosis and treatment. In the future, we would like to attempt extirpation of mediastinal tumor from the neck by endoscopy without thoracotomy.
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