My clinical approach
Myelolipoma is one of the most easily recognizable adrenal findings on imaging. The characteristic fat content on CT permits confident diagnosis without biopsy. Our goal is to avoid both unnecessary surgery and complacency — we always pair the diagnosis with full hormonal workup to exclude coexisting pathology.
What is myelolipoma?
Benign tumor of the adrenal cortex composed of mature fatty tissue interspersed with hematopoietic elements (bone marrow). Non-functioning. Frequency 7-15% of adrenal incidentalomas. Usually unilateral, rarely bilateral.
Symptoms
- Most often asymptomatic (incidental finding).
- In large lesions: back/flank pain, fullness sensation.
- Rare: spontaneous hemorrhage (hemoperitoneum, retroperitoneal bleed) in tumors > 6 cm.
- Coexistence with other adrenal pathologies (~10%).
Diagnosis
- CT: macroscopic fat content (HU < -30) is essentially pathognomonic.
- Chemical-shift MRI confirms fat content.
- Ultrasound: hyperechoic mass.
- Hormonal workup (1-mg DST, metanephrines, ARR if hypertensive) to exclude other pathology — per ESE/ENSAT 2023.
- Biopsy NOT necessary — never recommended for clearly characterized myelolipomas.
Treatment
- Observation for asymptomatic myelolipomas regardless of size if typical features.
- Laparoscopic adrenalectomy for: tumors > 6-7 cm, symptomatic (pain, hemorrhage), equivocal imaging, rapid growth.
- Conservative management always preferred when safe — avoid unnecessary surgery.
Follow-up
For clearly characterized myelolipomas < 4 cm, ESE/ENSAT 2023 does not recommend repeat imaging. Lesions 4-6 cm may be reassessed at 12 months. Larger or symptomatic lesions warrant surgical consultation.
Bottom line: Myelolipoma is almost always a "quiet" diagnosis. Proper imaging and complete hormonal workup permit safe observation without unnecessary surgery.
Frequently Asked Questions (FAQ)
What is an adrenal myelolipoma?
A rare benign tumor composed of mature fatty tissue and hematopoietic elements. Non-functioning. Frequency ~7-15% of adrenal incidentalomas.
Is it dangerous?
No. The vast majority are asymptomatic and harmless. In rare cases, large tumors (> 6-10 cm) may spontaneously hemorrhage or cause local pressure symptoms.
How is it diagnosed?
Characteristic CT appearance due to high fat content (HU < -30 in fatty areas), essentially pathognomonic. Chemical-shift MRI confirms. Hormonal workup is needed only to exclude coexisting pathology.
When is surgery needed?
Tumors > 6-7 cm, symptomatic (pain, hemorrhage), or with equivocal imaging. Laparoscopic adrenalectomy is the standard approach.
How is follow-up done?
For small asymptomatic myelolipomas < 4 cm with typical imaging, ESE/ENSAT 2023 does not recommend repeat imaging. Intermediate (4-6 cm) lesions can be reassessed at 12 months.
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References
- Fassnacht M, et al. ESE/ENSAT clinical practice guideline on the management of adrenal incidentalomas (2023) — academic.oup.com
- Decmann Á, et al. Adrenal myelolipoma: a comprehensive review — Endocrine (2018) — pubmed.ncbi.nlm.nih.gov
Medical Review
Dr. Marinos Vasilas, Urologist — Andrologist
Dr. Marinos Vasilas evaluates adrenal myelolipomas with a conservative approach and multidisciplinary discussion when surgical decision is required.
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