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Difficulty: MediumBreast and Endocrine Surgery

A 58-year-old man undergoes a non-contrast computed tomography (CT) scan of the abdomen and pelvis in the emergency department for severe left flank pain. The scan reveals a 4-mm calculus in the left distal ureter, which he subsequently passes. Incidentally, a 3.2-cm mass is discovered in the right adrenal gland. The mass is homogeneous, has smooth margins, and shows an attenuation of 8 Hounsfield units (HU). He has a history of hypertension well-controlled on lisinopril. His blood pressure is 134/86 mm Hg, and his pulse is 76/min. Physical examination reveals a normal body habitus with no abdominal striae, proximal muscle weakness, or easily bruised skin. Which of the following is the most appropriate next step in the management of this patient's adrenal finding?

  1. A
    CT-guided fine-needle aspiration of the adrenal mass
  2. Measurement of plasma free metanephrines, 1-mg overnight dexamethasone suppression test, and aldosterone-to-renin ratioAnswer
  3. C
    Unilateral laparoscopic adrenalectomy
  4. D
    Reassurance and repeat non-contrast abdominal CT scan in 12 months
  5. E
    Measurement of random morning serum cortisol and adrenocorticotropic hormone (ACTH)

Answer

The correct answer is the biochemical evaluation including plasma free metanephrines, an overnight dexamethasone suppression test, and an aldosterone-to-renin ratio.
The correct response outlines the comprehensive biochemical screening required for all adrenal incidentalomas. Because incidentalomas can secrete hormones without causing overt clinical symptoms (e.g., subclinical Cushing syndrome), functional testing is mandatory. The standard panel includes a 1-mg overnight dexamethasone suppression test (for hypercortisolism) and plasma free metanephrines or 24-hour urine fractionated metanephrines (for pheochromocytoma). In patients with concomitant hypertension or hypokalemia, a plasma aldosterone-to-renin ratio must also be obtained to screen for primary hyperaldosteronism.

Step-by-Step Solution

1
Identify the clinical scenario.
The patient has an asymptomatic 3.2-cm right adrenal incidentaloma with a low unenhanced attenuation of 8 HU.
Characterizing the mass's size and density helps determine its malignant potential.
2
Evaluate the imaging characteristics.
The mass is less than 4 cm and has a low unenhanced attenuation (<10 HU), which strongly suggests a benign, lipid-rich adrenal adenoma.
Imaging features guide the initial stratification of surgical risk versus the need for biochemical workup.
3
Determine the necessary diagnostic algorithm for adrenal incidentalomas.
All adrenal incidentalomas require biochemical testing to rule out subclinical hormone hypersecretion, even if they appear morphologically benign on imaging.
Subclinical functioning adenomas (e.g., mild hypercortisolism, primary hyperaldosteronism) can cause long-term cardiovascular and metabolic morbidity.
4
Select the appropriate biochemical tests.
Testing must include screening for pheochromocytoma (metanephrines), Cushing syndrome (dexamethasone suppression test), and primary hyperaldosteronism (aldosterone-to-renin ratio, specifically indicated because the patient has hypertension).
These tests effectively screen for the most common clinically significant functional adrenal tumors.

Key Concept

All adrenal incidentalomas require a complete biochemical evaluation to rule out hormone hypersecretion, including screening for pheochromocytoma, hypercortisolism, and (if hypertensive) primary hyperaldosteronism, regardless of benign imaging characteristics.
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Topics

Breast and Endocrine Surgery

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