Parathyroid Adenoma Presenting as a Giant Cystic Neck Mass

We present a case report of a parathyroid adenoma, which presented as a giant cystic neck mass while providing thorough reviews of the pathophysiology of parathyroid adenomas and the differential diagnosis for large, cystic neck masses in adults. A 72 year old female presented to a tertiary academic medical center with a complicated past medical history and was found to have an asymptomatic central neck mass which measured 10.5 × 7.7 × 4.1 cm on ultrasound and extended from the retropharyngeal space with mass effect on the hypopharynx, esophagus, trachea, and right carotid space structures as well as the superior mediastinum. She had elevated calcium and parathyroid hormone (PTH) levels. She underwent surgical excision of this mass and had an uneventful postoperative period. Large cystic neck masses generate a wide differential diagnosis. In adults, it is important to consider the rare possibility of parathyroid adenoma, especially in patients who may not be able to communicate vague symptoms of hypercalcemia. This particular parathyroid adenoma is several orders of magnitude larger than an average parathyroid adenoma and its massive size served as a distraction for the proper diagnosis as large, cystic neck masses in adults are to be considered cancer until proven otherwise.