Evaluation of Adrenal Incidentaloma

Initial Evaluation

The American College of Radiology recommends that fine-needle aspiration biopsy should be reserved for cases in which noninvasive techniques are equivocal, not as an initial evaluation tool, due to significant risks including bleeding, pneumothorax, infection, and potential tumor seeding along the needle track 1, 3
Adrenal biopsy carries significant risks including bleeding (8-12% complication rate), pneumothorax, infection, and potential tumor seeding along the needle track, making biochemical exclusion of pheochromocytoma mandatory before any biopsy 4, 5
Biochemical exclusion of pheochromocytoma is mandatory before any biopsy, as several deaths have been reported after adrenal biopsies of undiagnosed pheochromocytomas 6, 7

Non-contrast CT is the first-line imaging test to characterize adrenal masses, with lesions with <10 HU on non-contrast CT likely being benign adenomas 3, 4, 5, 8
Chemical shift MRI is indicated if lesion is identified only on contrast-enhanced CT and further characterization is required 2, 3

Follow-up CT or MRI at 3-6 months is appropriate for initial evaluation of indeterminate lesions to assess for growth or changes in imaging characteristics that might suggest malignancy 2, 3, 6

Measurement of urinary catecholamines or metanephrines is recommended to exclude pheochromocytoma 7, 9
24-hour urinary VMA level is appropriate as part of initial hormonal screening for pheochromocytoma 9