What is the recommended management for a patient with a thickened left adrenal gland consistent with benign adrenal hyperplasia and a newly identified lipomatous lesion in the right adrenal gland consistent with an adrenal myelolipoma?

Management of Benign Adrenal Hyperplasia and Adrenal Myelolipoma

No further imaging or hormonal follow-up is required for either the stable left adrenal hyperplasia or the newly identified right adrenal myelolipoma, provided initial hormonal screening is completed and both lesions are non-functional. 1, 2

Initial Hormonal Evaluation Required

Before discontinuing surveillance, complete the following one-time hormonal assessment:

• 1 mg overnight dexamethasone suppression test to exclude autonomous cortisol secretion 1
• Aldosterone-to-renin ratio only if the patient has hypertension or hypokalemia 1
• Plasma or 24-hour urinary metanephrines if either mass showed >10 HU on non-contrast CT or if signs of catecholamine excess are present 1

The myelolipoma's lipomatous composition on CT makes it radiologically benign and does not require pheochromocytoma screening if it demonstrates characteristic fat density. 1

Management Algorithm by Lesion Type

Left Adrenal Hyperplasia (Stable, Thickened)

• If non-functional and stable: No further imaging or hormonal testing is needed 1, 2
• If functional (hyperaldosteronism): Medical management with spironolactone or eplerenone is recommended for bilateral adrenal hyperplasia rather than surgery 1
• The stability on serial imaging essentially eliminates malignancy risk 2

Right Adrenal Myelolipoma (Newly Identified, Lipomatous)

Myelolipomas containing macroscopic fat detected on initial CT do not require further follow-up imaging or functional testing. 1

• Myelolipomas are benign, hormonally inactive tumors composed of mature adipose tissue and hematopoietic elements 3, 4, 5
• The lipomatous appearance on CT (negative Hounsfield units in fat-containing areas) confirms the diagnosis with >90% accuracy 4, 6

Size-Based Surgical Indications for Myelolipoma

Surgery is not indicated for asymptomatic myelolipomas based on current presentation, but should be considered if:

• Size >6-7 cm: Risk of spontaneous hemorrhage, rupture, or mass effect increases significantly 4, 7, 6
• Symptomatic: Chronic pain, mass effect on surrounding structures, or compression of adjacent organs 3, 7, 6
• Rapid growth >5 mm/year: Requires repeat hormonal work-up and surgical evaluation 1, 8

For asymptomatic myelolipomas <4 cm, surveillance is sufficient. 4, 6

Critical Pitfalls to Avoid

• Do not perform adrenal biopsy for either lesion—it is contraindicated for adrenal incidentalomas unless there is known extra-adrenal malignancy requiring confirmation of metastatic disease 1, 9
• Do not continue routine imaging for radiologically benign, non-functional masses <4 cm, as malignant transformation risk is essentially 0% 2
• Do not skip initial hormonal screening even for radiologically benign lesions, as approximately 5% have subclinical hormone production requiring treatment 9
• Do not assume bilateral lesions represent metastatic disease—the combination of stable hyperplasia and myelolipoma is consistent with benign pathology 8, 4

When to Resume Surveillance

Only resume imaging or hormonal testing if:

• New hormonal symptoms develop (hypertension, hypokalemia, virilization, Cushing's features) 1, 2
• New abdominal pain or palpable mass suggesting myelolipoma enlargement or hemorrhage 4, 7, 6
• Growth >3 mm/year on any incidental repeat imaging obtained for other reasons 1, 8

Annual symptom screening is reasonable given that 17% of initially non-functional masses develop hormone secretion after 1 year, increasing to 47% by 5 years. 2