Radiologic evaluation of incidentally discovered adrenal masses.

The increasing use of cross-sectional imaging has led to an increase in the incidental discovery of adrenal masses (adrenal incidentalomas). Although most of these lesions are benign, they often present a diagnostic dilemma. Before creating a management plan, the physician should determine if the lesion is benign or malignant and if the lesion is functioning or nonfunctioning. Incidentally discovered adrenal masses usually are benign adenomas; however, myelolipomas, cysts, hemorrhage, pheochromocytomas, metastases, and adrenocortical carcinomas are also possible. Unenhanced computed tomography and chemical shift magnetic resonance imaging can characterize most adenomas because the lesions have high lipid content. Contrast-enhanced computed tomography can further characterize the adenomas because of the washout characteristics with iodinated intravenous contrast media. Fluorodeoxyglucose- positron emission tomography can be helpful in characterizing some lesions, and biopsy is rarely required. This article summarizes the American College of Radiology Appropriateness Criteria for the use of imaging modalities and biopsy to characterize incidentally discovered adrenal masses.