Adrenal Myelolipoma

Adrenal myelolipoma is a benign tumour of mature fat and haematopoietic tissue.

Accounts for 3 to 7% of adrenal incidentalomas; usually unilateral, in middle aged adults.

Mostly hormonally inactive; associated with obesity, hypertension, congenital adrenal hyperplasia (bilateral large lesions).

Complications: spontaneous retroperitoneal haemorrhage (large lesions).

• Usually asymptomatic incidental finding.
• Flank or abdominal pain, mass effect for large lesions (over 6 cm).
• Acute pain, shock with haemorrhage (Wunderlich syndrome).

• CT: heterogeneous mass with macroscopic fat (density below minus 30 HU) and calcifications.
• MRI: signal drop on fat suppression.
• Hormonal screening: dexamethasone suppression test, plasma metanephrines, aldosterone/renin if hypertensive, 17 hydroxyprogesterone in bilateral disease.
• Biopsy rarely needed (typical imaging is diagnostic); exclude liposarcoma, adrenocortical carcinoma.

• Observation with imaging at 6 to 12 months then periodically for lesions under 6 cm without symptoms.
• Surgery (laparoscopic adrenalectomy) for symptomatic lesions, rapid growth, haemorrhage, diagnostic uncertainty, or large size (over 6 to 10 cm).
• Treat functional abnormalities or congenital adrenal hyperplasia (hydrocortisone, fludrocortisone).
• Embolisation for acute haemorrhage in unstable patients.