Polyarteritis Nodosa Confined to the Kidneys in a Patient with Proteinuria and Mild Renal Impairment

Polyarteritis nodosa (PAN) is a systemic necrotizing vasculitis predominantly involving medium- or small-sized arteries, typically of the kidneys and other internal organs. Given the rarity of PAN and the variable clinical presentation, diagnosis is challenging and, to date, no definitive diagnostic marker has been identified. A patient diagnosed with immunoglobulin A nephropathy was observed to exhibit deterioration in renal function. To determine whether new structural abnormalities had developed, computed tomography scans of the kidneys, ureters, and bladder were obtained. Both kidneys exhibited multiple cortical defects, and a renal angiogram was performed to determine the cause. Angiography revealed partial obliteration of the left distal renal artery branches and multifocal extensive infarctions in both kidneys, and the patient was diagnosed with renal-limited PAN. Following steroid monotherapy, an improvement in renal function was observed. We believe that this case report may be helpful to physicians who assess and treat patients with suspected renal-limited PAN.