Xanthogranulomatous pyelonephritis presenting as Proteus preperitoneal abscess

Xanthogranulomatous pyelonephritis (XGPN) is a rare form of chronic pyelonephritis with progressive loss of renal function. Commonly, obstructing urinary calculi are seen. It is difficult to differentiate between XGPN and malignancy in many cases, and the diagnosis is usually only confirmed post-operatively upon histopathological examination of the specimen. Surgical treatment is often the main treatment modality due to suspicion for malignancy. Here, we present a case of XGPN that presented with abdominal distension, which was eventually discovered to be due to a preperitoneal abscess.