Management of 3.7 cm Adrenal Myelolipoma
No further imaging follow-up or functional testing is required for this patient's 3.7 cm adrenal myelolipoma. 1
Definitive Guideline Recommendation
The 2023 CUA/AUA guideline explicitly states that patients with myelolipomas and other small masses containing macroscopic fat detected on initial work-up do not require further follow-up imaging or functional testing, regardless of size below 4 cm. 1 This recommendation applies directly to your patient's 3.7 cm lesion that is radiologically compatible with myelolipoma on CT.
Why No Follow-Up Is Needed
Myelolipomas are definitively benign tumors composed of mature fat and hematopoietic elements that can be diagnosed with certainty on CT imaging due to their pathognomonic appearance showing macroscopic fat. 2, 3
Key characteristics supporting conservative management:
- Myelolipomas never undergo malignant transformation - they are benign lipomatous tumors with zero malignant potential 3
- Natural history studies demonstrate safety of observation - in a series of 16 myelolipomas followed for average 3.2 years, 13 patients remained asymptomatic despite variable growth patterns 4
- Size does not correlate with symptoms or complications - tumors can enlarge, decrease, or remain stable without clinical significance 4
When Surgery Would Be Indicated
Surgery is only necessary for myelolipomas in specific circumstances (none of which apply to your patient):
- Symptomatic mass effect causing persistent abdominal pain (not present in your patient) 4, 5
- Acute hemorrhage with hemodynamic instability (not present) 2, 3
- Very large size - generally considered when >10 cm, though this threshold is not absolute 4, 5
- Diagnostic uncertainty - if imaging features are atypical and diagnosis cannot be confirmed 2, 5
Critical Pitfall to Avoid
Do not perform routine hormonal screening for isolated myelolipomas. While the guideline recommends hormonal evaluation for adrenal incidentalomas generally 1, myelolipomas are hormonally inactive tumors. 3, 5 The only exception is if there is clinical suspicion of a concomitant functional adenoma or if the patient has congenital adrenal hyperplasia (which increases myelolipoma prevalence). 3
Practical Management Algorithm
For this specific patient:
- Confirm the diagnosis - Ensure CT demonstrates macroscopic fat (negative Hounsfield units in portions of the mass), which is diagnostic 2
- Reassure the patient - Explain this is a benign finding requiring no treatment 1
- No repeat imaging - Do not schedule follow-up CT or MRI 1
- Focus on the renal stone - Direct clinical attention to managing the 4 mm calculus and JJ stent removal 1
Size Threshold Clarification
The guideline's 4 cm threshold for repeat imaging applies to non-functional adenomas, not myelolipomas. 1 Myelolipomas are specifically exempted from this follow-up requirement because their fat content makes them definitively diagnosable as benign. 1 At 3.7 cm, this lesion falls into the category requiring no action.