Evolution of renal segmental atrophy (Ask-Upmark kidney) in children with vesicoureteric reflux: radiographic and morphologic studies.

A radiographic and morphologic study of nine patients with renal segmental "hypoplasia," whose kidneys were radiographically normal when first examined, showed the lesion to be a form of localized, progressive renal atrophy. The renal abnormality bears a strong relationship to vesicoureteric reflux, which could be demonstrated in every patient. No evidence of renal scarring or atrophy was observed in initial roentgenographic examinations at a mean age of 2.9 years (range 0.1 to 10 years); however, serial studies during five to 14 years after discovery of vesicoureteral reflux demonstrated both a lack of renal growth and a progressive loss of substance irrespective of infection. Radiographic lengths of scarred kidneys, as measures of renal growth, correlated poorly with the radiographic surface areas of the renal parenchymal outlines. The mean time from discovery of vesicoureteric reflux to appearance of a renal scar was 6.1 years, and to onset of hypertension in six patients was 7.8 years. The renal abnormality consisted of lobar atrophy with variable tubular atrophy and glomerular sclerosis and with parenchymal destruction that in some specimens had proceeded to a complete loss of nephronic elements. The occasional presence of relatively well-preserved glomeruli and tubules and of focal segmental sclerosis within persisting glomeruli was taken as evidence of a progressive renal abnormality, as opposed to a static developmental hypoplasia. These observations indicate that renal scarring, the injury presumably having been initiated by vesicoureteric reflux, can progress despite correction of the reflux and despite prevention of urinary tract infection.