Xanthogranulomatous pyelonephritis in childhood

Demographic data, clinical presentation, associated abnormalities, and radiologic findings were evaluated to outline diagnostic criteria that may lead to the diagnosis of xanthogranulomatous pyelonephritis in children.

Eleven boys and 8 girls with a mean age of 3.4 +/- 1.7 years were classified into obstructive xanthogranulomatous pyelonephritis (n = 13), which was associated with nephrolithiasis and nonobstructive (n = 6), which mimicked Wilms' tumor.

Twelve children with obstructive diffuse involvement of the renal parenchyma, 1 with left-sided obstructive focal involvement in a horseshoe kidney (group 1), and 6 with nonobstructive diffuse xanthogranulomatous pyelonephritis (group 2) showed a male to female ratio of 1.2:1 and 2:1, respectively. Mean age was 4.1 +/- 1.2 years in group 1 versus 1.8 +/- 1.5 years in group 2; P =.001. The common features were renal mass, hematuria, and anemia (100%; P =.07) and leucocytosis (77% v 83%; P =.097). Main differences between the 2 groups were acute inflammatory syndrome (0 v 33%; P =.01), recurrent urinary infection (54% v 17%; P =.05), isolation of Proteus mirabilis as a pathogen (69% v 0; P =.001), and renal stones (100% v 0; P =.001). Preoperative diagnosis was accurate in all 13 (100%) children with obstructive xanthogranulomatous pyelonephritis. Radiologic features that were not consistent with Wilms' tumor in group 2 were absence of sharp definition and encapsulation of the mass, ill-defined margins with inflammatory infiltration of the perinephric fat and focal inflammatory tissue destruction. Nephrectomy was technically difficult because of extensive adhesions to the retroperitoneum, psoas muscle, and surrounding structures in both groups.

Xanthogranulomatous pyelonephritis must be considered in the differential diagnosis of a child presenting with a renal mass, anemia, and elevated inflammatory markers. Treatment by nephrectomy is curative. J Pediatr Surg 36:598-601.