What is the appropriate investigation for incidental adrenal hyperplasia found on a Computed Tomography (CT) scan?

From the Guidelines

Incidental adrenal hyperplasia found on CT scan should be investigated with a focused history and physical examination, followed by non-contrast CT as first-line imaging to distinguish benign lesions from those requiring further radiologic investigation, as recommended by the most recent guidelines 1. The initial assessment should include a detailed history focusing on symptoms of hormonal excess and physical examination.

• Laboratory testing should include screening for autonomous cortisol secretion with 1 mg dexamethasone suppression testing, as well as screening for primary aldosteronism with an aldosterone-to-renin ratio in patients with hypertension and/or hypokalemia 1.
• Patients with signs or symptoms of catecholamine excess or adrenal masses displaying >10 HU on non-contrast CT should be screened for pheochromocytoma with plasma or 24-hour urinary metanephrines 1.
• Adrenal mass biopsy should not be performed routinely for the work-up of an adrenal incidentaloma, and adrenal vein sampling is recommended prior to offering adrenalectomy in patients with primary aldosteronism 1. The investigation is crucial because adrenal hyperplasia can be associated with various conditions ranging from benign physiological responses to serious hormonal disorders that require specific treatment.
• For non-functional adrenal hyperplasia, follow-up imaging in 6-12 months is typically advised to monitor for changes, and adrenalectomy should be considered for patients with adrenal incidentalomas growing >5 mm/year after repeating a functional work-up 1.
• Shared decision-making between patients and their clinicians should be used for the management of indeterminate non-functional adrenal lesions, including options for repeat imaging or surgical resection 1.

From the Research

Investigation of Incidental Adrenal Hyperplasia

• The evaluation of incidentally discovered adrenal masses, including adrenal hyperplasia, should involve assessment of malignant potential via imaging characteristics and adrenal hormone excess via clinical and biochemical features 2.
• Adrenal hyperplasia is non-malignant enlargement of the adrenal glands, which is often bilateral, and can be incidental or related to indolent disease process, and may be related to benign or malignant etiologies causing biochemical alterations in the hypothalamic-pituitary-adrenal axis 3.
• Initial evaluation of adrenal incidentalomas, including adrenal hyperplasia, should be aimed at ruling out malignancy and functionality, and should include a detailed clinical history, radiographic assessment, and complete blood chemistry and hormone study 4.

Imaging Characteristics

• Computed Tomography (CT) is the primary modality of choice for adult adrenal imaging, owing to reproducibility, temporal and spatial resolution, and broader access 3.
• CT scan without contrast is the initial radiographic test of choice for characterization of adrenal incidentalomas, including adrenal hyperplasia 4.
• Noncontrast and contrast computed tomography attenuation values expressed in Hounsfield units is the best tool to differentiate between benign and malignant adrenal masses 5.

Biochemical Evaluation

• All patients with adrenal incidentalomas, including adrenal hyperplasia, should undergo hormonal evaluation for subclinical Cushing's syndrome and pheochromocytoma, and those with hypertension should also be evaluated for hyperaldosteronism 5.
• Combined 1-mg dexamethasone suppression test, plasma metanephrines, and aldosterone/plasma renin activity measurements (if hypertensive) are reasonable initial hormonal evaluations 5.
• 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 5.

Follow-up and Treatment

• Patients with autonomous cortisol secretion with comorbidities potentially related to hypercortisolism, particularly if they are young and there is a poor control, may benefit from unilateral adrenalectomy 4.
• The indication for unilateral adrenalectomy is clear in patients with overt hormonal syndromes or suspected malignancy 4.
• Adrenal tumors with indeterminate radiological features that grow to at least 0.8 cm over 3-12 months may be considered for surgical resection 5.