Is hormonal evaluation recommended for an 8x9 mm lipomatous (fatty) lesion in the medial limb of the right adrenal gland?

Hormonal Evaluation for 8x9 mm Adrenal Lipomatous Lesion

Yes, hormonal evaluation should be performed for an 8x9 mm lipomatous lesion in the medial limb of the right adrenal gland, even though it is small and likely benign. 1

Rationale for Hormonal Evaluation

All adrenal incidentalomas, regardless of size or appearance, require hormonal evaluation to rule out subclinical hormone secretion. This is because:

• 5-23% of incidentally discovered adrenal masses demonstrate subclinical hormone secretion without obvious clinical symptoms 2, 1
• All current guidelines recommend initial hormonal testing for any newly discovered adrenal incidentaloma 2, 1
• Even small, benign-appearing lesions can be hormonally active and require treatment

Recommended Hormonal Tests

The following tests should be performed:

1. 1mg overnight dexamethasone suppression test to screen for cortisol excess 1
2. Plasma free metanephrines or 24-hour urinary fractionated metanephrines to rule out pheochromocytoma 1
3. Aldosterone-to-renin ratio only if the patient has hypertension or hypokalemia 2, 1

Imaging Characteristics and Follow-up

For this 8x9 mm lipomatous adrenal lesion:

• The small size (< 1 cm) and lipomatous (fatty) characteristics strongly suggest a benign lesion, likely a myelolipoma or lipoma 1, 3
• Myelolipomas account for approximately 90% of adrenal lipomatous tumors 3
• The risk of malignancy is extremely low for lesions < 3 cm, especially those with lipomatous features 2, 1

If the lesion is confirmed to be non-functioning and has definitive benign imaging characteristics (lipomatous appearance):

• No further imaging follow-up is required for clearly benign lesions < 4 cm 1
• If there is any uncertainty about the benign nature, a follow-up CT or MRI in 6-12 months may be considered 1

Management Considerations

• If hormonally inactive: No surgical intervention is needed for this small (8x9 mm) lipomatous lesion 1, 3
• If hormonally active: Surgical removal should be considered regardless of size 1

Important Caveats

• Ensure the lipomatous nature is confirmed on non-contrast CT (Hounsfield Units < 10) 2, 1
• Even though the lesion is small, do not skip hormonal evaluation, as subclinical hormone secretion can occur regardless of size 2
• The American College of Radiology guidelines emphasize that even asymptomatic adrenal masses can have subclinical function 2

Following these guidelines will ensure proper evaluation of this small adrenal lipomatous lesion while avoiding unnecessary procedures for what is most likely a benign, non-functioning adrenal tumor.