Xanthogranulomatous pyelonephritis: a reappraisal.

A survey was undertaken of the clinical, radiological, ultrasonic, and pathological features of 80 patients with xanthogranulomatous pyelonephritis (XPN). The condition is a progressive granulomatous reaction to chronic renal inflammation which is often suppurative and usually caused by calculous urinary tract obstruction. The characteristic pathological features are large numbers of foam cells containing lipid, and the presence of inflammatory destruction of neighbouring renal tissue. XPN, which is commoner than generally recognised, may often be diagnosed preoperatively--the patient is usually a middle-aged female who presents with severe toxaemia, tender loin mass, and mild lower urinary tract symptoms. The diagnosis is confirmed by radiology and ultrasonography. Nephrectomy is curative.