Chapter 25: Adrenal Gland
A computed tomography (CT) scan is obtained on a 60-year-old patient with suspected acute diverticulitis. In addition to findings consistent with diverticulitis of the sigmoid colon, he is found to have a 2-cm homogeneous left adrenal mass, as seen in Fig. 25-1. Which of the following is true concerning the further workup of the adrenal mass?
FIGURE 25-1. CT scan of a left-sided, benign adrenal adenoma.
(A) Biopsy should be performed, followed by biochemical workup.
(B) Given the patient’s age, this is likely a metastatic lesion from a nonadrenal primary.
(C) Normal serum aldosterone, in the face of normokalemia and normal blood pressure, essentially rules out functional aldosteronoma.
(D) Normal plasma cortisol level essentially rules out cortisol-producing adrenocortical adenoma.
(C) Adrenal incidentalomas are masses discovered on the adrenal gland during radiologic imaging for other reasons. The reported incidence is 5%. Among patients with adrenal incidentalomas, approximately 80% have nonfunctional adenomas, 5% have subclinical Cushing’s syndrome, 5% have pheochromocytoma, fewer than 5% have adrenal cortical carcinoma, 2.5% have metastatic lesions, and the rest may be ganglioneuromas, myelolipomas, or benign cysts. Cortical adenomas are usually small and homogeneous, with a smooth, encapsulated margin on CT scan. They usually do not enhance with intravenous contrast and are usually low-attenuation lesions (less than 10 Hounsfield units) when intravenous contrast is not used. Important questions to address when evaluating an adrenal incidentaloma are as follows: (1) Functional status: Is the lesion hormonally active? (2) Radiologic characteristics: Does the lesion have radiographic features suggestive of a malignancy? (3) Medical history: Does the patient have a previous history of cancer?
Serum biochemical tests can rule out functional cortical adenomas. Functional aldosteronomas cause hypertension, hypokalemia, weakness, and polyuria. Laboratory abnormalities include elevated serum aldosterone, hypokalemia, and suppressed renin activity. Functional aldosteronoma is unlikely in a patient without hypertension and with normal serum potassium. Functional cortisol-producing adenomas usually cause Cushing’s syndrome, characterized by weight gain, hypertension, easy bruisability, diabetes mellitus, and centripetal obesity (“buffalo hump” and “moon face”) (Fig. 25-3).
FIGURE 25-3. Characteristic features of Cushing’s syndrome (from Brunicardi FC, Andersen DK, Billiar TR, et al., (eds.), Schwartz’s Principles of Surgery. 9th ed. New York, NY: McGraw-Hill; 2010: Fig. 38-42. Copyright © The McGraw-Hill Companies, Inc., All rights reserved).
Because the total amount of daily cortisol secreted in these patients can be normal, 24-h urine collection for cortisol may be normal, and this test is not sensitive. Random serum tests for cortisol are not helpful, as these patients lose the normal diurnal variation in cortisol secretion. The simplest test to screen for ...