Fibromuscular dysplasia with clotted renal artery aneurysm.

A six-year-old girl presented with hypertension and headaches. IVP demonstrated a subtle calcification medial to the left kidney and a non-functioning lower pole raising concern for tumor. Color Doppler ultrasound demonstrated normal flow to the upper pole of the left kidney and a severely attenuated avascular lower pole, which was confirmed with selective angiography. Pathology of the surgically resected left kidney showed a calcified large renal artery aneurysm containing thrombus associated with fibromuscular dysplasia. Unique findings in this case were the presence of wall calcification and intraluminal clot in the aneurysm which resulted in nonvisualization of the aneurysm and absent flow to the lower pole.