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CUAJ – CUA Best Practice Report Guo et al
BPL: AML management

to respond well to mTOR inhibitors. In contrast, there is currently no indication nor data supporting the
treatment of sporadic AML with mTOR inhibitor therapy. In patients with synchronous bilateral AMLs
or clinical symptoms consistent with hereditary conditions, referral for further assessment and genetic
testing should be discussed. The vast majority of AMLs in children are associated with syndromic
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conditions. Sporadic AMLs are extremely rare in children with minimal published data available. Given
the paucity of data and experience for children diagnosed with AMLs on imaging, referral to a tertiary
pediatric center should be strongly considered. This Best Practice Report (BPR) will focus on the
sporadic form of AML in adults only.
Diagnosis, follow up protocol, as well as indications for and type of management for the
sporadic AML vary widely. This BPR seeks to codify existing data to provide practicing urologists with
the best evidence-based recommendations to inform decision making in the management of sporadic
AML. The following clinical questions will be discussed:
1. What imaging tests are necessary to confirm the diagnosis of AMLs?
2. What is the natural history of AMLs?
3. What is the optimum follow up protocol for AMLs under observation?
4. What are the indications for intervention?
5. What interventions are available and preferred?
6. What is the management of acutely bleeding AMLs?

Methods
The search strategy registered on PROSPERO and was done electronically on OVID using MEDLINE
and EMBASE. Given the limited amount of literature on the subject, articles regarding diagnosis and
treatment were all grouped together in one search. Search terms included “angiomyolipoma OR AML”
and excluded “liver OR hepatic,” “tuberous sclerosis OR TSC,” “lymphangioleiomyomatosis OR
LAM,” “case report.” The search was limited to peer-reviewed articles published in English since 1995
with adult (age > 18) human subjects. 468 studies were screened, and 159 studies underwent full-text
review. Disagreements between the two reviewers (Y.G. & P.C.) were resolved by consensus. In
general, there were no prospective comparative trials available. Reported patient, lesions, and outcomes
varied significantly. There were no prospective comparative trials identified (Fig. 1).

Diagnosis

Recommendation #1: All cases of suspected renal AML should be confirmed with either
unenhanced CT, contrast-enhanced CT, or MRI. Percutaneous biopsy should be considered if
neither CT nor MRI are diagnostic.

The radiological diagnosis of AMLs is dependent on the detection of intertumoral fat. On ultrasound, the
fat content in these lesions result in a characteristic appearance of a hyperreflective lesion with acoustic
shadowing. However, up to 30% of small (< 3cm) renal cell carcinomas (RCC) can mimic this
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appearance, reducing the specificity of US. There is also a small proportion of AMLs (5%) that have