Can subcentimetre ultrasound detected angiomyolipomas be safely disregarded?

To optimise follow-up by dismissing lesions on baseline ultrasound (US) if renal lesions conform to US criteria of an angiomyolipoma (AML).

The present study was a 10-year retrospective review of patients who were found to have incidental hyperechoic renal lesions on US to ascertain the outcome from subsequent imaging, clinical encounters, and cancer registrations. Exclusions included renal calculi, tuberous sclerosis, Von-Hippel-Lindau, or a known cancer.

After excluding 39 patients, 1,493 patients were identified. One hundred and sixty had more than one lesion with 87 patients having bilateral lesions. Regardless of indication, 889 patients had subsequent imaging within 5 years (59.5%). The average size of all AMLs was 13.2 mm. In the group with lesions that were <10 mm (807), 438 had imaging follow-up with an average follow-up time of 1.5 years. Mean lesion size in this group was 7 mm, with an average increase of <0.5 mm on follow-up. No lesions were found to be malignant on subsequent imaging nor did any of these patients have a subsequent renal cancer diagnosis registered at local multidisciplinary team meetings.

No incidental subcentimetre hyperechoic renal lesion with imaging characteristics of an AML demonstrated significant growth or developed into a malignancy on follow-up.