Epithelioid angiomyolipomas (EAML) are rare variants of the more common renal angiomyolipoma. They have malignant potential.
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Pathology
Like more common renal angiomyolipomas, EAMLs are considered perivascular epithelioid cell tumors (PEComas). EAMLs were regarded as a separate renal mass entity by the WHO in 2016.
Radiographic features
Epithelioid angiomyolipomas do not have a specific appearance. Some features that have been associated with them:
CT
- hyper-attenuating mass with variable enhancement 3
MRI
- T2: hypointense
- IP/OOP imaging: signal dropout of microscopic fat content on OOP
- DWI/ADC: hyperintense on DWI
- T1 C+: marked hypervascularity with rapid washout
Differential diagnosis
The imaging appearance is similar to renal cell carcinoma and AML with minimal fat.
The diagnosis can be considered if a renal mass has small foci of macroscopic fat without calcification, which would be atypical for renal cell carcinoma. Renal biopsy would be needed for confirmation, however.