Surgical Managment of a Forearm Arteriovenous Fistula in a Child with Noonan Syndrome: A Case Report

Peripheral arteriovenous fistulas (AVFs) are rare vascular anomalies in children and typically result from trauma or iatrogenic injury.To the best of our knowledge, we report the first case of a peripheral AVF associated with genetically confirmed CBL syndrome (Noonan syndrome-like disorder).A 5-year-old boy with CBL syndrome presented with a two-week history of progressive swelling, prominent superficial veins, and a palpable thrill in the right forearm.He had no known history of trauma or invasive procedures involving the affected extremity.Genetic testing had revealed a heterozygous pathogenic variant in the CBL gene (c.1100A>C,p.Gln367Pro).Physical examination revealed marked swelling in the antecubital region, dilated tortuous veins, a strong continuous thrill over the antecubital fossa, and an audible vascular bruit.Distal pulses were intact with no signs of ischemia.Computed tomography angiography demonstrated a direct abnormal connection between the brachial artery and basilic vein at the antecubital level.Color Doppler ultrasonography confirmed arterialized venous flow patterns.Comprehensive preoperative coagulation studies were within the normal limits.Under general anesthesia, surgical exploration identified a 5 mm wide fistulous connection between the brachial artery and basilic vein.The fistula was primarily repaired with 7-0 polypropylene sutures.Postoperatively, the thrill disappeared with preserved distal pulses.Postoperative Doppler ultrasonography confirmed complete fistula closure.At one-year followup, the patient remained asymptomatic with excellent extremity perfusion and no evidence of recurrence.Cranial magnetic resonance imaging and thoracic computed tomography revealed no evidence of intracranial or intrathoracic vascular malformations on available imaging.This case expands the vascular phenotype of RASopathies and suggests a link between RAS-MAPK dysregulation and peripheral AVF development.Clinicians should maintain heightened awareness for peripheral vascular anomalies in syndromic patients, even without a trauma history.