XPN is a rare form of chronic pyelonephritis. It is more common in middle age women. Clinical presentation involves malaise, fever, flank pain, weight loss, and is usually associated to urinary calculi or UTI. Usual laboratory findings include anemia, high CRP and liver dysfunction. As for images, both computed tomography and magnetic resonance imaging can show characteristic findings and the extension of the lesion. Antibiotics may be given in case of acute infection, but the treatment of choice is nephrectomy, with the objective of removing all the compromised tissue.