Medical and surgical evaluation and treatment of adrenal incidentalomas.

INTRODUCTION: Adrenal incidentalomas are detected in approximately 4% of patients undergoing high-resolution abdominal imaging studies. The majority of adrenal incidentalomas are benign, but careful evaluation of all patients is warranted to be certain that primary adrenocortical carcinoma and functional adenomas are not missed.

METHODS: The diagnostic approach in patients with adrenal incidentalomas should focus on two main questions: whether the lesion is malignant, and whether it is hormonally active. Radiological evaluation including noncontrast and contrast computed tomography attenuation values expressed in Hounsfield units is the best tool to differentiate between benign and malignant adrenal masses. All adrenal tumors with suspicious radiological findings, most functional tumors, and all tumors more than 4 cm in size that lack characteristic benign imaging features should be surgically excised. All patients should undergo hormonal evaluation for subclinical Cushing's syndrome and pheochromocytoma, and those with hypertension should also be evaluated for hyperaldosteronism. Combined 1-mg dexamethasone suppression test, plasma metanephrines, and aldosterone/plasma renin activity measurements (if hypertensive) are reasonable initial hormonal evaluations.

RESULTS: Annual biochemical follow-up of most patients with adrenal incidentalomas, especially if the tumor is more than 3 cm in size, for up to 5 yr may be reasonable. Patients with adrenal masses less than 4 cm in size and a noncontrast attenuation value of more than 10 Hounsfield units should have a repeat computed tomography study in 3-6 months and then yearly for 2 yr. Adrenal tumors with indeterminate radiological features that grow to at least 0.8 cm over 3-12 months may be considered for surgical resection.