History: 20 year old female with back pain and urinary tract infection. This is a case of xanthogranulomatous pyelonephritis, which is defined as a chronic infection of the kidney and surrounding structures, destruction of renal parenchyma, and infiltration with lipid-laden macrophages. It is the lipid-laden macrophages which characteristically give this entity its name “xanthogranulomatous.” Xanthos … Continue reading