Presentation
Patient with a past medical history significant for hypertension, depression, and urinary retention secondary to blood clots presents with gross hematuria. CT urogram was performed for further evaluation.
Patient Data
Noncontrast CT images demonstrate a well-circumscribed mass within the left renal pelvis with associated surrounding vessels. There is residual contrast within the collecting system from a prior CT study performed at a different hospital which was unavailable.
Post-contrast images demonstrate a 4.3cm vascular lesion within the left renal pelvis with several small surrounding saccular outpouchings, as well as feeding and draining vessels. The left renal vein is enlarged, likely related to component of shunting.
US was also performed the same day. Grey-scale US images demonstrate a 4.6 cm anechoic structure in the left renal hilum. Color and Spectral doppler images demonstrate areas of color mosaicism in the adjacent soft tissue related to vibration surrounding the structure.
The left main renal artery and vein were difficult to identify with certainty, limiting assessment of spectral waveforms, though there is likely high-velocity and low resistance within the artery and turbulent and pulsatile flow in draining veins.
Case Discussion
Patient subsequently underwent a left renal angiogram which demonstrated a large arteriovenous fistula with associated aneurysmal component supplied by the lower pole renal artery. The fistula was embolized without complications. Follow-up CT demonstrated a diminished caliber of the left renal vein, suggesting resolution of high flow shunting.
Key points:
aneurysms, arteriovenous malformations, and arteriovenous fistulas may mimic a renal mass
they are more common in renal transplants than in native kidneys
typically incidental, but can present with flank pain, gross hematuria, urination retention, hypertension, heart failure, renal insufficiency and ultimately massive hemorrhage or thromboembolic events
more commonly acquired, as opposed to arteriovenous malformations, which are developmental
color doppler images can show flashes of color in the adjacent renal parenchyma related to vibration
spectral doppler wave forms in the feeding artery typically show high-velocities and low resistance. The draining vein can show turbulent, pulsatile, and arterialized flow
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