Xanthogranulomatous Pyelonephritis Associated with Actinomycosis Misdiagnosed as a Metastatic Kidney Cancer

Xanthogranulomatous pyelonephritis (XP) is an uncommon, chronic, destructive, granulomatous disease of the renal parenchyma. The condition is generally associated with long-term urinary tract obstruction and infection, although the precise etiology of disease remains unknown. The condition often mimics neoplastic and inflammatory diseases, and XP associated with actinomycosis is extremely uncommon. A 60 year-old male was admitted complaining of abdominal pain and weight loss. His radiological findings were suggestive of metastatic kidney cancer, and we performed radical laparoscopic nephrectomy and mesenterectomy for diagnostic purposes. Pathologically, actinomycosis combined with XP was evident. We report here a rare case of XP associated with actinomycosis. (Korean J Med 2016;90:78-82)