Approach to the Patient With Adrenal Incidentaloma

Abstract

Adrenal tumors are commonly discovered incidentally on cross-sectional abdominal imaging performed for reasons other than adrenal mass. Incidence of adrenal tumors increased 10-fold in the past 2 decades, with most diagnosed in older adults. In any patient with a newly discovered adrenal mass, determining whether the adrenal mass is malignant and whether it is hormonally active is equally important to guide the best management. Malignancy is diagnosed in 5% to 8% of patients with adrenal tumors, with a higher risk in young patients, if history of extra-adrenal malignancy, in those with large adrenal tumors with indeterminate imaging characteristics, and in bilateral adrenal tumors. Although overt hormone excess is uncommon in adrenal incidentalomas, mild autonomous cortisol secretion can be diagnosed in up to 30% to 50% of patients. Because autonomous cortisol secretion is associated with increased cardiovascular morbidity and metabolic abnormalities, all patients with adrenal incidentalomas require work up with dexamethasone suppression test. Management of adrenal tumors varies based on etiology, associated comorbidities, and patient's preference. This article reviews the current evidence on the diagnosis and evaluation of patients with adrenal mass and focuses on management of the most common etiologies of adrenal incidentalomas.

Keywords: Hounsfield units; adrenal mass; dexamethasone suppression test; diagnosis; hormonal work up; imaging; malignancy.

Figure 1.

Computed tomography (CT) imaging of adrenal incidentalomas. (A) Adrenocortical adenoma, left, 2.2 cm, Hounsfield units (HU) of -12 on unenhanced CT. (B) Adrenocortical carcinoma, left, 6.8 cm, HU of 35 on unenhanced CT. (C) Pheochromocytoma, left, 7.7 cm, HU 42 on unenhanced CT. (D) Bilateral adrenal metastases, melanoma, 4.5 right and 2.8 cm left, HU of 25 to 27 on unenhanced CT. (E) Sarcoma, left, 5.1 cm, HU of 36 on unenhanced CT. (F). Lymphoma, left, 9.7 cm, heterogeneous on contrast enhanced CT. (G) Bilateral myelolipomas, 12.7 cm right and 2.6 left, with areas of macroscopic fat on contrast enhanced CT. (H) Ganglioneuroma, right, 2.6 cm, HU of 18 on unenhanced CT. (I) Bilateral adrenal hyperplasia, 2.4 cm right and 2.6 cm left, HU of 7 on unenhanced CT.

Figure 2.

Adrenal incidentaloma work up: evaluation for etiology. In a patient with newly diagnosed incidental adrenal mass, imaging characteristics should be examined. Risk of malignancy and/or pheochromocytoma is stratified based on the unenhanced computed tomography attenuation of the adrenal mass (measured in HU). If HU of a homogeneous adrenal mass is <10, the benign adrenal mass pathway should be followed. If the HU of a homogeneous adrenal mass is >10, or the mass is heterogeneous, the pathway for the indeterminate or suspicious adrenal mass should be followed. Tumor size and laterality of the adrenal mass should be examined next. The size of the circle is proportional to the prevalence of each entity. The line that divides the tumor size (<4 cm and >4 cm) and laterality (unilateral vs bilateral) further indicates the proportion of each tumor entity falling within each cutoff. Further considerations in the indeterminate/suspicious adrenal mass pathway include the (1) findings of the hormonal work up, (2) demographics, (3) history of extra-adrenal malignancy, and (4) presence of the genetic syndrome. Additional testing and management are suggested based on suspected etiology. Abbreviations: ACC, adrenocortical carcinoma; CT, computed tomography; HU, Hounsfield units; MRI, magnetic resonance imaging; Pheo, pheochromocytoma. *If the tumor is heterogeneous on imaging, proceed with the pathway for “>20 HU.” Created with BioRender.com.

Figure 3.

Adrenal incidentaloma evaluation: clinical and hormonal assessment. Abbreviations: 1-mg DST, 1-mg overnight dexamethasone suppression test; ACC, adrenocortical cancer; DHEA-S, dehydroepiandrosterone sulfate.

Figure 4.

Approach to adrenal adenoma with autonomous cortisol secretion. Abbreviations: 1-mg DST, 1-mg overnight dexamethasone suppression test; 8-mg DST, 8-mg overnight dexamethasone suppression test; ARMC5, Armadillo Repeat Containing 5 gene; DHEA-S, dehydroepiandrosterone sulfate; MACS, mild autonomous cortisol secretion.