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The incidental finding of one or more adrenal masses, discovered on a radiological study performed for reasons other than suspected adrenal disease, has become a common occurrence in modern medical practice. Because the differential diagnosis for these masses, termed adrenal incidentalomas, incudes multiple distinct clinical entities (of differing prognostic significance), surgical oncologists must be familiar with the appropriate diagnostic workup and management of these lesions. This requires not only an understanding of adrenal anatomy, pathophysiology, biochemistry, genetics, and differential diagnosis, but also a working knowledge of the upstream hypothalamic-pituitary axis, which regulates adrenal function.
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The prevalence of adrenal incidentalomas depends on the resolution of the imaging modality used, with the most sensitive computed tomography (CT) scanners identifying unexpected adrenal masses in up to 4% of abdominal scans.1,2 Prevalence is also proportional to age, varying from approximately 1% among individuals less than 30 years old to 10% in those over 70.3-5 Bilateral lesions are present in 10% to 15% of cases and autopsy series indicate equal prevalence among men and women. Adrenal incidentalomas are also more common among patients diagnosed with hypertension, diabetes, and/or obesity.1,3,5,6
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DIAGNOSTIC EVALUATION
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The workup of a newly diagnosed adrenal incidentaloma begins with a thorough history and physical exam, with emphasis placed on two questions: (1) Is excess adrenal hormone production present? and (2) Is primary malignancy or metastatic disease present?
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Abdominal and/or flank pain resulting from the development of an adrenal mass is unusual and, when present, often connotes an adrenal malignancy and poor prognosis. These symptoms may also be limited to large adrenal masses, usually >6 cm in diameter, or to masses for which rapid enlargement has occurred (usually the result of intralesional hemorrhage). The majority of adrenal incidentalomas do not produce abdominal pain, regardless of their size.
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With the exception of metastatic disease involving the adrenal gland(s), all adrenal incidentalomas represent abnormal growth of adrenal tissue. As such, all the patients must be evaluated for associated overproduction of adrenal hormones, including catecholamines (pheochromocytoma), cortisol (Cushing's syndrome and subclinical Cushing's syndrome), aldosterone (Conn's syndrome), and sex steroids (virilization or feminization—usually associated with adrenocortical carcinoma). This assessment begins with careful evaluation for the presence of associated symptoms (Table 41-1) and is followed by biochemical testing.
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In addition to hormonal testing, all patients diagnosed with an adrenal incidentaloma should undergo CT scanning. The ...