Spectrum of renal findings in pediatric fibromuscular dysplasia and neurofibromatosis type 1.

Background: Fibromuscular dysplasia (FMD) and neurofibromatosis type 1 (NF1) are the most common causes of pediatric renal artery stenosis (RAS) in western countries, and characterization of their angiographic features could aid in an accurate diagnosis and in treatment.

Objective: This study characterizes renal angiographic findings in pediatric fibromuscular dysplasia (FMD) and neurofibromatosis type 1(NF1).

Materials And Methods: We reviewed 68 angiograms performed over 11 years on 43 children with renovascular hypertension (20 male, 23 females; ages 1 month to -19 years; median/average 9.8 years). Ten patients were diagnosed with NF1, and 33 had presumed FMD. The frequency, extent and distribution of lesions were determined and analyzed.

Results: Stenosis was found in 91% of patients (n=39/43), with 86% showing stenosis of 1st or 2nd order arteries, and 12% distal to 2nd order. Stenoses in multiple 1st/2nd order arteries were found in 32% of patients, and 36/43 patients had 1-2 stenoses. The most common lesion was a ≤ 5 mm stenosis in a 1st/2nd order artery, in 42%. Mean percentage of stenosis in a 1st/2nd order vessel was 62%; ≥ 70% stenosis was found in 53%, and ≥ 90% stenosis in 29%. Bilateral disease was noted in 30% of patients. Intraparenchymal disease, distal to 2nd order branches, was seen in 30%. Aneurysms were seen in 28%, beading in 19% and collaterals in 51% (associated with ≥ 70% stenosis). Mid-aortic narrowing was seen in 16%, more often in patients with NF1.

Conclusion: We provide a descriptive characterization of renal angiographic findings in pediatric FMD and NF1.