Breaking the Rules: Nonclassic Appearances of Parathyroid Adenomas

At many institutions, 4D-CT has become the first-line technique for localizing candidate parathyroid adenomas before surgical resection. The appearance of the classic parathyroid adenoma on 4D-CT is well described in the literature, including enhancement pattern, morphology, and typical locations. However, readers of 4D-CT are quick to learn that many parathyroid adenomas do not conform to this conventional appearance. We will review both the classic appearance of parathyroid adenoma on 4D-CT as well as variations in appearance and location that are important to know for successful lesion localization. Familiarity with histologically proved adenomas that deviate from the classic appearance enables practicing neuroradiologists to more effectively identify potential candidate lesions, aiding the surgeon in rendering a cure.Learning Objective: To describe the nonclassic appearance of parathyroid adenomas to improve preoperative identification of candidate lesions