Management of 2.6 cm Adrenal Adenoma with Benign Imaging Features
No further follow-up imaging or functional testing is required for this patient. 1
Rationale for No Further Surveillance
Your patient has a 2.6 cm left adrenal mass with definitive benign imaging characteristics that meet all criteria for a lipid-rich adenoma:
- Hounsfield units <10 on unenhanced CT (diagnostic threshold for benign adenoma) 1
- Absolute washout >70% (far exceeds the 60% threshold for benignity) 2, 3
- Size <4 cm (below the threshold requiring surveillance) 1
The 2023 CUA/AUA guidelines explicitly state that "patients with benign non-functional adenomas <4 cm...do not require further follow-up imaging or functional testing." 1 This recommendation is based on the extremely high specificity (100%) of these combined imaging criteria in predicting benign lesions. 3
Required Initial Hormonal Evaluation
Despite the benign imaging appearance, all patients with adrenal incidentalomas require comprehensive hormonal screening before concluding management. 1, 4
You must perform the following tests:
- 1 mg overnight dexamethasone suppression test (screening for autonomous cortisol secretion) 1, 4
- Plasma metanephrines or 24-hour urinary fractionated metanephrines (screening for pheochromocytoma—critical because approximately 1/3 of pheochromocytomas can paradoxically show adenoma-like washout characteristics) 1, 4
- Aldosterone-to-renin ratio and serum potassium if the patient has hypertension or hypokalemia 1, 4
This hormonal evaluation is mandatory even though the imaging strongly suggests a benign adenoma, because approximately 5% of radiologically benign incidentalomas have subclinical hormone production requiring treatment. 5
Why No Surveillance Is Needed
The combination of imaging features in your patient provides 100% specificity for benign disease:
- Studies examining adrenalectomy specimens confirm that all masses with HU <10 and washout >60% were benign on final pathology 3
- The risk of finding adrenocortical carcinoma is 0% when HU <10 1
- Size <4 cm in patients without known extra-adrenal malignancy carries only a 1.5% malignancy rate, and all malignant lesions in this population were >5 cm 1
Critical Pitfalls to Avoid
Do not order adrenal biopsy. Biopsy is contraindicated for adrenal incidentalomas and should only be considered when diagnosing metastatic disease from a known extra-adrenal malignancy would change management—and only after excluding pheochromocytoma. 1
Do not skip hormonal evaluation despite benign imaging. Radiological appearance cannot reliably predict hormone secretion status, and subtle hormone production can have significant clinical implications for the patient's cardiovascular and metabolic health. 4
Ensure the patient is truly asymptomatic. Specifically assess for signs of cortisol excess (weight gain, easy bruising, proximal muscle weakness, striae), catecholamine excess (paroxysmal hypertension, headaches, palpitations, diaphoresis), or aldosterone excess (resistant hypertension, hypokalemia). 1
If Hormonal Testing Is Normal
Once hormonal evaluation confirms the mass is non-functional, no further imaging or biochemical follow-up is required. 1 The patient can be reassured that this represents a benign, non-functional adrenal adenoma requiring no treatment or surveillance.