Management of the patient with incidental bilateral adrenal nodules

Bilateral incidental adrenal nodules represent 10–23% of all incidental adrenal nodules. The general approach to these nodules follows the same premise as for unilateral incidental adrenal nodules however there are features unique to bilateral nodules including the differential diagnosis, the diagnostic approach as well as the management. The majority (75%) of bilateral truly incidental adrenal nodules are benign nonfunctioning adenomas however bilateral lesions are more likely to display hormone excess than unilateral lesions with subclinical Cushing's being the most prevalent abnormality followed by Cushing's syndrome, Hyperaldosteronism as well as Congenital Adrenal Hyperplasia (CAH). Though bilateral pheochromocytomas are less common, a patient presenting with bilateral pheochromocytomas will usually have a germline pathogenic variant and be syndromic. The overall diagnostic approach to bilateral nodules involves determining based on the patients' clinical history and examination as well as the imaging phenotype of each lesion whether the lesions could represent a malignancy, exhibit hormonal excess and whether they could represent a familial syndrome. In patients with bilateral infiltrative lesions, adrenal insufficiency needs to be excluded. In patients with bilateral myelolipomas, screening for CAH should be considered. We present an illustrative case of a patient with incidental bilateral nodules and review the systematic approach to the patient including the key radiographic diagnostic features of adrenal nodules (unenhanced CT attenuation, adrenal washout and chemical shift MRI) to best determine the etiology of these lesions. An overview of the management of patients with such bilateral adrenal nodules is provided with a particular focus on pheochromocytomas.