Perianeurysmal Retroperitoneal Fibrosis Presenting As Acute Kidney Injury: A Case Report

Retroperitoneal fibrosis and chronic periaortitis describe overlapping groups of rare diseases characterized by inflammation and fibrosis involving the aorta. The presentation is often non-specific, and while obstructive nephropathy is a common complication, these entities are an uncommon cause of renal failure necessitating dialysis. A 57-year-old man presented multiple times with acute kidney injury, even requiring hemodialysis, with repeated abrupt resolution. Renal ultrasound repeatedly did not reveal acute hydronephrosis. Renal biopsy on his first admission showed acute tubular injury attributed to hypovolemia. Computed tomography finally revealed a retroperitoneal soft tissue mass encasing the infrarenal abdominal aorta and partially encasing the bilateral ureters. Bilateral nephrostomy tubes were placed, steroids were initiated, and the patient experienced rapid and remarkable improvement in renal function. Chronic periaortitis should be considered in older patients with acute kidney injury, even in the absence of ultrasonographic evidence of obstruction. Additional studies are needed to describe the test characteristics of renal sonography for periaortitis, the long-term sequelae of acute kidney injury secondary to periaortitis, and the optimal management to preserve longterm renal function.