Renal Papillary Necrosis Complicating Immune Checkpoint Inhibitor Therapy

Renal papillary necrosis (RPN) is a particular form of renal injury characterized by necrosis of the renal papilla identified through imaging and histological investigation. RPN generally occurs in the setting of urinary obstruction, urinary infection, sickle cell disease, diabetes mellitus, or nonsteroidal anti-inflammatory drug use. We present a case of RPN in a patient on immune checkpoint inhibitor (ICI) therapy who developed immunotherapy-induced severe colitis followed by obstructive acute kidney injury (AKI). The patient lacked other risk factors for RPN. Initial imaging with computed tomography of the abdomen and pelvis without contrast showed bilateral perinephric edema, mild bilateral hydroureteronephrosis, and high attenuation material at bilateral ureterovescular junctions. Supportive care with isotonic fluids led to passage of tissue in urine and AKI recovery. Contrast-enhanced computed tomography performed 3 weeks after AKI hospitalization revealed multiple pyramids with a bullseye enhancement pattern consistent with prior RPN. Although ICIs have well-recognized nephrotoxicity, this case is the first to describe RPN in the setting of an ICI immune-related adverse event.