[Acute kidney injury due to retroperitoneal fibrosis: complexities of diagnosis and treatment].

Retroperitoneal fibrosis (RPF) is a rare cause of postrenal acute kidney injury (AKI). We present a clinical case of a 65-year-old patient who developed acute right-sided hydronephrosis with postrenal AKI. Contrast-enhanced computed tomography showed dilation of the ureter, pelvis and calyxes on the right, diminished size of the left kidney and signs of RPF, including fat tissue thickening, compaction and stranding along the aorta and its visceral branches, mesenteric sinuses, thickening of the peritoneum at the level of the paracolic gutters, pelvic tissue compaction, descending and infrarenal abdominal aortic aneurisms, subocclusion of the left renal artery, and atherosclerosis of the visceral arteries. The patient received hemodialysis. IgG4-related RPF was diagnosed. A 6Ch/24 cm stent was placed in the right ureter, after that AKI resolved. Patients with RPF require multidisciplinary approach for timely diagnosis and successful treatment.