Adrenal Cortical Adenoma

Adrenal cortical adenomas are benign tumors that stem from the cortex of the adrenal gland. These adenomas are frequently discovered as adrenal incidentalomas, adrenal tumors confirmed on imaging during a workup for unrelated causes. Nearly 85% of adrenal incidentalomas are benign and nonfunctional [1] [2]. Functioning adrenal cortical adenomas may cause hypertension, orthostatic hypotension, and tachycardia. A physical exam may reveal central obesity, hirsutism, striae, and gynecomastia. An ophthalmologic exam may reveal retinopathy secondary to chronic hypertension. Endocrine diseases resulting from functioning adrenal cortical adenomas reflect the excess production of adrenal gland hormones such as aldosterone (primary aldosteronism), cortisol (Cushing's syndrome), and sex hormones.

Primary aldosteronism is not characterized by a specific clinical presentation. These patients may have unprovoked hypokalemia and hypertension although potassium levels can be normal [3]. As a result of hypernatremia, hypokalemic alkalosis, and other related mechanisms, patients may develop fatigue, weakness, headaches, tetany, and paresthesias. Also, polyuria and polydipsia could result from hypokalemia-induced nephrogenic diabetes insipidus. Complications secondary to chronic hypertension include renal, cardiac, neurologic, and ophthalmologic manifestations.

Cushing's syndrome is characterized by weakness, bruising, weight gain, and depression. Affected individuals may also develop osteoporosis and metabolic syndrome [4].

Finally, androgen or estrogen-secreting tumors may cause virilization in females and feminization in males.

All individuals suspected to have adrenal cortical adenoma, whether based on symptoms or an incidental finding on imaging, need a detailed assessment. The workup should include a personal and family history, a thorough physical exam, and appropriate studies.

In the evaluation of adrenal incidentalomas, it is very important to consider the possibility of pheochromocytoma [5]. To identify a pheochromocytoma, the first-line test is the measurement of plasma fractionated metanephrines and normetanephrines and/or 24-hour urine collection of metanephrines and catecholamines [6].

Primary aldosteronism is confirmed with the ratio of plasma aldosterone concentration to plasma renin activity [7]. Moreover, the diagnosis is likely when the aldosterone–to–renin ratio is above 30 and the plasma aldosterone level is elevated (>0.5 nmol/L) [8]. Also, an electrolyte panel should be obtained in these patients.

An important test in the diagnosis of Cushing's syndrome is an overnight dexamethasone suppression test [9]. Other considerations in these patients include screening for metabolic syndrome with a lipid panel and glucose tolerance test.

Patients with virilization or feminization should be tested for androgens and estrogens respectively.

On unenhanced computed tomography (CT) scan, adrenal cortical adenoma is characterized by a low attenuation which reflects the presence of an abundant intracytoplasmatic fat [10]. Also, CT and magnetic resonance imaging (MRI) are both effective in discriminating between benign and malignant masses. Additionally, positron-emission tomography (PET) with 18F-fluorodeoxyglucose (18F-FDG) demonstrates excellent sensitivity for confirming adrenal malignancy [11].

Fine-needle aspiration has limited value and is reserved for cases in which all other findings are inconclusive [12].

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