Radiological Case: Cirsoid Renal Arteriovenous Malformation

David Kenny, DO; Nicholas Petruzzi, MD; Thomas Egizi; Robin Camp


Appl Radiol. 2016;45(6):35-37. 

In This Article


Renal arteriovenous malformations (AVM) are rare lesions that can be congenital or acquired. Acquired AVMs are more common, accounting for approximately 70% of cases, and typically are a result of previous biopsy, trauma, infection, malignancy, or renal surgery. Congenital AVMs accounts for the other 20%. Although the exact cause of congenital AVMs is unknown, it is thought to be associated with a defect in the elastic component of the vessel. There are two variants of congenital AVMs. "Cirsoid" variant are described as having a tortuous knotted appearance of multiple arterial vessels with interconnecting fistula. The other variant, called "cavernous" or "angiomatous," has a single arterial vessel supply that feeds many small connecting fistulas.[2] Acquired AVMs are characterized by a single direct communication between an artery and a vein without an intervening vascular nidus.[3] Congenital AVMs usually present with hematuria in up to 72% of cases, while acquired AVMs are more likely to present with hemodynamic changes, such as hypertension, cardiomegaly and congestive heart failure.[1] The peak incidence occurs in patients between 30 and 40 years of age and women are affected twice as much as men.[4]

The gold standard for diagnosing renal AVM is angiography. Color Doppler US is the first-line imaging due to its low cost and ability to easily identify turbulent flow. However, lighter-colored flow of a small AVM can be obscured by the flow of normal vessels grouped in the hilum. Additionally, Color Doppler US has difficulty differentiating between the turbulent flow of an AVM and the flow from an aneurysm.[6] Mulitdecetor Row CT has improved the depiction of the renal veins in the early stage of the arterial phase; allowing for minimally invasive, three-dimensional visualization of the arteries and veins.[7] Classic magnetic resonance imaging is capable of distinguishing high-flow malformations suggestive of AVMs as demonstrated by areas of multiple flow voids on gradient-echo images.[8] Although MRI without contrast can be a useful imaging modality in patients with concerning renal function or with contraindications for CT, it is often more costly and time consuming than other available modalities.[9]