What are the management and treatment options for a patient with a left adrenal mass?

Management of Left Adrenal Mass

All patients with a left adrenal mass require both hormonal evaluation to exclude functional tumors and imaging characterization to assess malignancy risk, with management decisions based on size, imaging characteristics, and functional status. 1, 2

Initial Diagnostic Workup

Mandatory Hormonal Screening

Every patient requires the following tests regardless of how benign the mass appears on imaging, as approximately 5% of radiologically benign incidentalomas have subclinical hormone production requiring treatment 2:

• 1 mg overnight dexamethasone suppression test (give 1 mg at 11 PM, measure serum cortisol at 8 AM) to screen for autonomous cortisol secretion 2, 3
• Plasma free metanephrines or 24-hour urinary metanephrines/normetanephrines to exclude pheochromocytoma 2, 3
• Aldosterone-to-renin ratio only if the patient has hypertension and/or hypokalemia 2, 3

Imaging Characterization

• Obtain unenhanced CT to measure Hounsfield units (HU) 2, 3
• If HU ≤10: definitively benign lipid-rich adenoma 2
• If HU >10: proceed with second-line imaging using either washout CT or chemical shift MRI 1, 2

Important caveat: Approximately one-third of pheochromocytomas may washout in the characteristic range of an adenoma on CT, and one-third of benign adenomas do not washout in the adenoma range, so clinicians must be aware of these limitations 1

Management Algorithm Based on Characterization

Benign Non-Functional Lesions <4 cm

• No further imaging or functional testing required if the mass is <10 HU, non-functional, and <4 cm 1, 2, 4
• This includes benign adenomas, myelolipomas, and other small masses containing macroscopic fat 1, 4
• Risk of malignant transformation is 0% to <1% 2, 4

Benign Non-Functional Lesions ≥4 cm

• Repeat imaging in 6-12 months even if radiologically benign (<10 HU) 1, 4
• Most surgically resected pheochromocytomas and adrenocortical carcinomas were >4 cm at diagnosis 4

Growth Rate Thresholds on Follow-up

• Growth <3 mm/year: No further imaging or functional testing required 1, 4
• Growth >5 mm/year: Adrenalectomy should be considered after repeating functional work-up 1, 4

Indeterminate Non-Functional Lesions

• Use shared decision-making with options including repeat imaging in 3-6 months versus surgical resection 1
• There are no strong data to guide the best approach in this scenario 1

Functional Lesions Requiring Surgery

Adrenalectomy is mandatory for: 1, 3

• Unilateral aldosterone-secreting adrenal masses
• Pheochromocytomas
• Cortisol-secreting masses with clinically apparent Cushing's syndrome

Minimally-invasive surgery should be performed when feasible for these procedures 1

For mild autonomous cortisol secretion (MACS), adrenalectomy should be considered only in younger patients with progressive metabolic comorbidities attributable to cortisol excess 2

Suspected Adrenocortical Carcinoma

• Minimally-invasive adrenalectomy can be offered if the tumor can be safely resected without rupturing the capsule 1
• Open adrenalectomy should be considered for larger tumors or those with locally advanced disease, lymph node metastases, or tumor thrombus 1

Special Populations

Young Adults, Children, and Pregnant Patients

• Adrenal lesions are more likely malignant in these populations, so evaluation should be expedited 1, 4
• Consider low-dose CT or chemical shift MRI as preferred first-line imaging to minimize radiation exposure 1

Patients with History of Extra-Adrenal Malignancy

• The rate of metastatic disease to the adrenal gland is 25-72% depending on the primary tumor type 2, 4
• These patients require closer evaluation even for smaller lesions 4

Bilateral Adrenal Masses

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

Critical Pitfalls to Avoid

• Never skip initial hormonal evaluation even if the mass appears benign on imaging, as functional abnormalities occur in approximately 5% of cases 2, 4
• Do not routinely perform adrenal mass biopsy for workup of an adrenal incidentaloma—it is rarely indicated and carries risks including potential tumor seeding 1, 2, 4
• Ensure pheochromocytoma is excluded before any biopsy if biopsy is being considered for suspected metastatic disease 1
• Avoid unnecessary repeated imaging for small adrenal masses with benign characteristics, as this increases radiation exposure, patient anxiety, and healthcare costs 2