Frequency of angiomyolipomas among echogenic nonshadowing renal masses (> 4 mm) found at ultrasound and the utility of MRI for diagnosis

Suresh de Silva*, Ross Copping, David Malouf, Anthony Hutton, Fiona Maclean, Peter Aslan

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

3 Citations (Scopus)


Objective. The purpose of this study is to evaluate what percentage of echogenic non-shadowing renal lesions larger than 4 mm found at ultrasound are angiomyolipomas (AMLs) and to review how to diagnose AMLs, with particular emphasis on the increasing role played by MRI.

Materials and methods. The study data were obtained at a single institution over a period of 45 months. Although some patients were being reviewed for specific symptoms, such as hematuria, pain, or recurrent urinary tract infections, most of the findings were incidental. Follow-up data on 158 lesions in 132 patients were available. Confirmation of diagnosis was made with follow-up imaging or with histopathologic examination.

Results. Ninety-eight (62.0%) of the lesions were AMLs, eight (5.1%) were renal cell carcinomas, three (1.9%) were oncocytomas, 17 (10.8%) were artifacts, seven (4.4%) were fat, five (3.2%) were calculi, another eight (5.1%) were scars, and 12 (7.6%) were complicated cysts. The mean age of patients with AML was significantly lower than that of patients without AML (61.71 [SD, 13.25] years vs 68.80 [SD, 17.85] years; p = 0.005). There was a female association with AMLs (p <0.001).

Conclusion. Echogenic non-shadowing renal lesions larger than 4 mm seen at ultrasound should not be assumed to represent an AML without follow-up because a percentage of renal cell carcinomas will be missed. Although certain ultrasound features can be useful in differentiating an AML from a renal cell carcinoma and CT is frequently diagnostic, an understanding of MRI is important because it can potentially detect lipid-poor AMLs.

Original languageEnglish
Pages (from-to)1074-1080
Number of pages7
JournalAmerican Journal of Roentgenology
Issue number5
Publication statusPublished - Nov 2017
Externally publishedYes


  • angiomyolipoma
  • echogenic renal lesion
  • MRI
  • renal cell carcinoma
  • ultrasound

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