Histopathologic Changes of Kidney in Pediatric UPJ Obstruction

Lee, Seung Eon; Han, Sang Won; Choi, Seung Kang; Jeong, Hyeon Joo

Abstract

INTRODUCTION AND OBJECTIVES: A kidney in the growing state and the possibility of spontaneous improvement are characteristics of the pediatric ureteropelvic junction obstruction (UPJO) that make the treatment of this disease difficult. We have tried to determine the histopathologic changes of the kidneys with UPJO relating to age, differential renal function and urinary tract infection (UTI).
METHODS
The total number of patients was 38 (40 kidneys). The age at the operation time was under 3 months in 9 cases (9 kidneys), 3 to 12 months in 10 cases (10 kidneys), and 1 to 18 years in 20 cases (21 kidneys). Needle biopsies from 3 different sites at the lower pole of the kidney were taken. The tissue was blindly observed for the presence of irreversible change (arteriolar thickening, glomerulosclerosis, interstitial fibrosis and periglomerular fibrosis) and reversible change (inflammatory cell infiltration) by light microscopy. Each pathological finding was graded as I, II or III, and each grade was given a numerical value. Statistical analysis was done with ANOVA.
RESULTS
Although the kidneys from patients under 3 months tended to show better histopathologic findings, there was no statistically significant difference in all 5 pathologic findings regardless of patient age. 5 cases (5 kidneys) with previous percutaneous nephrostomy (PCN) were not included in any group for analysis due to possible histologic changes of the renal parenchyma. Inflammatory cell infiltration, arteriolar thickening, glomerulosclerosis and periglomerular fibrosis were statistically significant in patients with previous or present UTI (14 kidneys) compared to the patients without UTI (26 kidneys). The patients with a mean differential renal function less than 30% (7 kidneys) as measured by DTPA or DMSA renal scan showed statistically significant changes in all of the 5 histopathologic findings compared to the patients with differential renal function greater than 30% (27 kidneys). 4 cases with bilateral UPJO (6 kidneys) were excluded from comparing the differential renal function. 5 kidneys with previous PCN had statistically significant degree of glomerulosclerosis compared to others.
CONCLUSIONS
Although we did not determine whether pediatric UPJO affects renal growth, it is probable that statistically significant irreversible histopathologic changes do not occur according to age. Considering histopathologic findings only, differential renal function and UTI Should be key factors in deciding the management of pediatric UPJO. In addition, PCN seems to induce more severe histopathologic changes of the kidney.