Acute Renal Infarction Caused by Renal Arteriovenous Fistula in a Patient with Fibromuscular Dysplasia: A Rare Case Report

Introduction: Acute renal infarction (ARI) is rare, typically caused by thromboembolism, cardiac pathology, cocaine abuse, or vascular disorders. Fibromuscular dysplasia (FMD), a non-atherosclerotic arteriopathy, can result in arterial stenosis, aneurysms (22.2%), or dissections (15-20%). Renal artery involvement occurs in 58–75% of patients with FMD, but renal infarction is rare (0.9%). Renal arteriovenous fistulas (rAVFs) are uncommon, usually post-traumatic or iatrogenic. We present an exceptional case of ARI secondary to rAVF in an FMD patient. Case Description: A 30-year-old woman presented with acute left flank pain (7/10). Initial evaluation revealed normal vital signs and left flank tenderness. Labs revealed elevated LDH (886 U/L), leukocytosis (WBC 12.5 K/μL), and proteinuria (UPCR: 583 mg/g). CT angiography showed left renal infarction, dilated renal vein, and cirrhosis. Normal serum Cr (0.5 mg/dL) without microscopic hematuria. The toxicology screen is negative. The hypercoagulability workup, echocardiography, and EKG were normal. Despite anticoagulation (heparin → enoxaparin), pain worsened (10/10) with gross hematuria. CT angiogram revealed progressive infarction, irregular left intrarenal arterial narrowing, and a large rAVF. Renal angiography confirmed complex rAVF, successfully embolized. Her pain improved post-procedure and discharged on apixaban. Discussion: ARI is frequently misdiagnosed due to nonspecific symptoms. FMD can lead to renal infarction via thromboembolism or vascular distortion. FMD should be considered in young patients with ARI without typical risk factors. While CT aids diagnosis, angiography is definitive. Endovascular embolization is pivotal in managing rAVF, highlighting its role in preventing further renal infarction, hypertension, and hematuria.1A: CT with contrast on admission day; 1B: CT angiogram on third day of admission; 1C: Renal angiogram on sixth day of admission.