Xanthogranulomatous pyelonephritis presenting as a pseudotumor in a 2-month-old boy.

The authors report on a 2-month-old boy presenting with a right renal mass. Investigations including ultrasound scan and computed tomogram were suggestive of a renal tumor. A right nephrectomy was performed with great difficulty because of dense adhesions to the adjacent structures. Cut section of the specimen showed the entire kidney to be replaced by cheesy-yellow areas. Histological examination was suggestive of xanthogranulomatous pyelonephritis. Although rare at this age, xanthogranulomatous pyelonephritis should be considered in the differential diagnosis of a renal mass in children. The lesion is unique among the inflammatory conditions in closely mimicking renal tumours clinically. A thorough histological examination also is suggested because the features can get confused easily with those of renal tumors.