Management of Adrenal Incidentaloma with Minimal Growth
For an adrenal incidentaloma that has grown from 1.2mm to 1.4mm over 2 years, no further imaging follow-up or functional testing is required as this represents growth of less than 3mm/year, indicating a benign lesion. 1
Initial Assessment of Adrenal Incidentalomas
- Most small (<3 cm) incidentally discovered adrenal masses in patients without a history of malignancy are benign, and extensive workup is usually not justified 1
- The differential diagnosis of adrenal incidentalomas includes benign non-functional adenomas (71-84%), functional adenomas (cortisol-secreting: 1-30%, aldosterone-secreting: 2-7%), pheochromocytomas (1.5-14%), and malignant lesions (adrenocortical carcinoma: 1.2-12%, metastases: 0-21%) 1
- Initial evaluation should include both imaging characterization and hormonal assessment to determine if the mass is benign or malignant and if it is hormonally active 1
Significance of Growth Rate
- The American Urological Association guidelines clearly state that no further imaging follow-up or functional testing is required for patients with adrenal lesions that grow <3mm/year on follow-up imaging 1
- Growth from 1.2mm to 1.4mm over 2 years represents only 0.1mm/year, which is well below the threshold of concern 1
- Studies have shown that small lipid-rich adrenal incidentalomas typically demonstrate minimal growth (mean 1±2mm over 5 years) and rarely develop hormonal hypersecretion during follow-up 2
Hormonal Evaluation
- Despite the minimal growth, it's important to note that all patients with adrenal incidentalomas should initially be screened for autonomous cortisol secretion using a 1mg overnight dexamethasone suppression test 3
- For patients with hypertension and/or hypokalemia, screening for primary aldosteronism with an aldosterone-to-renin ratio is recommended 3
- Screening for pheochromocytoma is not necessary for lesions with <10 Hounsfield Units (HU) on unenhanced CT and no signs or symptoms of catecholamine excess 1
Follow-up Recommendations
- Patients with benign non-functional adenomas <4 cm, myelolipomas, and other small masses containing macroscopic fat detected on the initial work-up do not require further follow-up imaging or functional testing 1
- Adrenalectomy should only be considered for adrenal incidentalomas growing >5 mm/year after repeating a functional work-up 1
- The growth rate of 0.2mm over 2 years in this case is minimal and not concerning for malignancy 1
Pitfalls to Avoid
- Avoid unnecessary repeated imaging for small adrenal masses with benign characteristics, as this leads to increased radiation exposure, patient anxiety, and healthcare costs 1
- Do not perform adrenal mass biopsy routinely for the work-up of an adrenal incidentaloma, as this is rarely indicated and carries risks 1
- Recognize that most small adrenal incidentalomas are benign adenomas, and the risk of malignant transformation of benign-appearing lesions is 0% to less than 1% 1
In conclusion, the minimal growth of 0.2mm over 2 years in this adrenal incidentaloma is well below the threshold of concern (3mm/year) and does not warrant further imaging or functional testing according to current guidelines.