Misleading imaging results in the diagnosis of parathyroid cysts.

Enlarged cystic parathyroid glands, whether hyperfunctioning or nonfunctioning, are rare and their accurate preoperative diagnosis is a difficult task. The authors report two cases of patients with cystic neck masses studied by Tl-201-Tc-99m pertechnetate subtraction scintigraphy, computerized tomography, and ultrasonography. The diagnostic consensus of preoperative studies was that these lesions were thyroid nodules or parathyroid adenomas. Surgical removal and histopathologic examination of these masses revealed a cystic parathyroid gland and a cystic parathyroid adenoma, respectively. When a fluid-filled lesion in the neck deep to the lower pole of the thyroid gland is encountered, the possibility of a parathyroid cyst should be considered so that further diagnostic tests can be properly performed.