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Updated: Aug 14, 2026
In Vivo, Percutaneous, Needle Based, Optical Coherence Tomography of Renal Masses
Published on: March 30, 2015
Imaging characteristics of minimal fat renal angiomyolipoma with histologic correlations
Jason Hafron1, James D Fogarty, David M Hoenig
1Department of Urology, Montefiore Medical Center/Albert Einstein College of Medicine, Bronx, New York, USA. jhafron@montefiore.org
Objectives:
To review our experience with minimal fat angiomyolipomas (AMLs) and correlate the confirmed pathologic diagnosis with preoperative radiologic features to evaluate the feasibility of an accurate diagnosis preoperatively. On rare occasions, renal AMLs contain minimal amounts of fat that are not identified on cross-sectional imaging.
Methods:
From November 1998 to August 2003, 6 patients (seven lesions) underwent renal surgery with the preoperative diagnosis of renal cell carcinoma as determined by preoperative imaging studies, and the finding of AML was unexpected. A single pathologist and radiologist reviewed all pathologic specimens and radiologic examinations. The characteristic findings were recorded and compared with those in published reports.
Results:
Pathologic review of the specimens demonstrated microscopic amounts of mature adipocytes, abnormally thickened blood vessels, and smooth muscle cells in all seven lesions. The mean estimated fat content was 4.1% (range 3% to 10%). Hounsfield unit measurement of the lesions on unenhanced computed tomography images revealed all lesions to be hyperdense relative to the normal kidney parenchyma and enhanced by at least 90 Hounsfield units or more with the administration of intravenous contrast. Enhancement was homogenous throughout each of the seven masses.
Conclusions:
Minimal fat renal AML tumors are typically hyperdense relative to the normal kidney parenchyma and demonstrate homogenous enhancement with the administration of intravenous contrast on computed tomography. These results may have important implications when planning partial versus radical nephrectomy by open or minimally invasive techniques.
Insights
Minimal fat renal angiomyolipomas (AMLs) often appear hyperdense on CT scans and show homogenous enhancement after contrast. This finding is crucial for accurate preoperative diagnosis, distinguishing them from renal cell carcinoma.
Area of Science:
- Radiology
- Pathology
- Urology
Background:
- Renal angiomyolipomas (AMLs) can rarely contain minimal fat, posing diagnostic challenges.
- Subtle fat content in AMLs may not be detected by standard cross-sectional imaging.
- Accurate preoperative diagnosis of renal masses is critical for treatment planning.
Purpose of the Study:
- To review experience with minimal fat AMLs.
- Correlate radiologic features with pathologic diagnosis for preoperative feasibility.
- Evaluate diagnostic accuracy of minimal fat renal AMLs.
Main Methods:
- Retrospective review of 6 patients (7 lesions) with unexpected AML findings after surgery.
- Pathologic specimens analyzed for fat, blood vessels, and smooth muscle.
- Radiologic examinations (CT) reviewed for lesion characteristics and enhancement patterns.
Main Results:
- Pathology confirmed microscopic fat (3-10%), thickened vessels, and smooth muscle in all lesions.
- CT showed hyperdense lesions relative to normal kidney parenchyma.
- All lesions demonstrated homogenous enhancement (>90 HU) post-contrast administration.
Conclusions:
- Minimal fat renal AMLs typically present as hyperdense masses with homogenous contrast enhancement on CT.
- These imaging characteristics aid in differentiating AMLs from other renal tumors preoperatively.
- Findings impact surgical planning, distinguishing between partial and radical nephrectomy.
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