Misdiagnosed giant parathyroid cyst: differential diagnosis of a neck mass of the central region

Parathyroid cysts (PCs) are rare benign lesions representing between the 0.08% and the 0.34% of the neck masses going on surgery. They should be considered in the differential diagnosis of neck masses, especially in the differential diagnosis of the cystic anterior neck masses. Approximately 300 cases of PC are reported within the international literature. The gold standard for diagnosis is the evidence of high-level intact parathyroid hormone in cystic fluid. It is important to diagnose PCs before surgery, not intraoperatively, in order to avoid unnecessary surgeries or superfluous excision of part of the thyroid gland and prevent the patient from iatrogenic hypothyroidism. A surgical approach is required in those patients with large-sized cysts, relapses despite needle aspirations or if it causes hyperparathyroidism. We describe a case report of a patient, initially misdiagnosed with a thyroid cyst swelling, who instead had a giant non-functioning PC, which produced dyspnoea or dysphagia.