What is the treatment algorithm for adrenal incidentaloma?

Treatment Algorithm for Adrenal Incidentaloma

The treatment algorithm for adrenal incidentaloma should follow a structured approach based on radiologic characteristics, hormonal evaluation, and size criteria to determine management decisions, with surgical intervention indicated for functional tumors, suspicious imaging features, or significant growth. 1

Initial Evaluation

Radiologic Assessment

• First-line imaging: Non-contrast CT to determine if the mass is benign or malignant 1
  • Benign features: Homogeneous, well-circumscribed, <10 Hounsfield Units (HU) 1
  • For indeterminate masses on non-contrast CT, proceed with second-line imaging: washout CT or chemical-shift MRI 1

Hormonal Evaluation

• All patients should undergo screening for autonomous cortisol secretion with 1 mg overnight dexamethasone suppression test 2, 3
• Patients with hypertension and/or hypokalemia should be screened for primary aldosteronism with aldosterone-to-renin ratio 1, 2
• Patients with adrenal masses >10 HU on non-contrast CT or with symptoms of catecholamine excess should be screened for pheochromocytoma with plasma or 24-hour urinary metanephrines 1, 2
• In cases of suspected adrenocortical carcinoma or virilization, perform serum androgen testing 1, 2

Management Decision Tree

Surgical Intervention Indicated For:

1. Functional tumors:

   • Unilateral cortisol-secreting masses with clinically apparent Cushing's syndrome 1
   • Aldosterone-secreting adrenal masses 1
   • Pheochromocytomas 1
   • Younger patients with mild autonomous cortisol secretion who have progressive metabolic comorbidities attributable to cortisol excess (after shared decision making) 1

2. Suspicious imaging features:

   • Masses >4 cm with inhomogeneous appearance or >20 HU 4
   • Minimally-invasive adrenalectomy for suspected adrenocortical carcinomas that can be safely resected without rupturing the tumor capsule 1
   • Open adrenalectomy for larger adrenocortical carcinomas or those with locally advanced features 1

3. Growth during follow-up:

   • Adrenal incidentalomas growing >5 mm/year (after repeating functional work-up) 1

Follow-up Without Surgery For:

1. Benign non-functional lesions <4 cm, myelolipomas, and other small masses containing macroscopic fat:

   • No further follow-up imaging or functional testing required 1

2. Radiologically benign (<10 HU) but ≥4 cm non-functional lesions:

   • Repeat imaging in 6-12 months 1

3. Lesions with minimal growth:

   • No further imaging or functional testing if growth <3 mm/year 1, 2
   • For growth between 3-5 mm/year, continued surveillance may be appropriate 2

4. Indeterminate non-functional lesions:

   • Management options include repeat imaging in 3-6 months versus surgical resection (shared decision-making) 1

Special Considerations

Bilateral Adrenal Incidentalomas

• Each lesion should be separately characterized following the same protocol as unilateral masses 1
• Consider measuring serum 17-hydroxyprogesterone to exclude congenital adrenal hyperplasia 1, 2
• Assess for adrenal insufficiency in suspected cases of bilateral infiltrative disease, metastases, or hemorrhage 1

Adrenal Biopsy

• Adrenal mass biopsy should not be performed routinely for the work-up of an adrenal incidentaloma 1
• Only consider when diagnosis of metastatic disease from an extra-adrenal malignancy would be of value 1

Common Pitfalls to Avoid

• Skipping hormonal evaluation even in apparently non-functioning tumors 3
• Relying solely on radiological appearance to predict hormone secretion status 3
• Performing adrenal biopsy without excluding pheochromocytoma, which can trigger life-threatening hypertensive crisis 3
• Failing to consider a multidisciplinary approach when imaging is not consistent with a benign lesion, there is evidence of hormone hypersecretion, significant tumor growth, or when surgery is being considered 1