[Clinical and histopathological characteristics of biopsy-proven renal diseases in Croatia]. / Klinicke i patohistoloske karakteristike biopsijom dokazanih bubreznih bolesti djece u Hrvatskoj.

There is little data on the spectrum of renal diseases in children in Croatia. The Croatian Society for Pediatric Nephrology has established the Registry of Biopsy-Proven Renal Diseases in an attempt to address this issue nationwide. Here we report preliminary results of a retrospective analysis of clinical and histopathological data of 565 children aged < or =17 years presenting to 9 hospitals in Croatia from 1991 to 2004, in whom kidney biopsy was performed. The most common indication for renal biopsy was nephrotic syndrome (39.1%), followed by asymptomatic proteinuria/hematuria (22.0%) and acute nephritic syndrome (17.0%). All biopsies were analysed by light-, immunofluorescent and electron microscopy. The majority of children, 552 out of 565 (92.4%), had glomerulonephritis (GN). Tubulointerstitial nephritis was found in 16 (2.8%), congenital renal parenchyma anomalies in 14 (2.5%) and vascular disease in 11 (1.9%) cases. One (0.2%) child had sarcoidosis with nephrocalcinosis. The sample was non-diagnostic in 1 (0.2%) case. Among children with GN, primary GN accounted for 70.9%, secondary GN for 16.1% and hereditary GN for 13.0% cases. The most frequent primary GN forms were focal segmental glomerulosclerosis (FSGS) (24.6%), mesangial proliferative glomerulonephritis (MEPGN) (19.2%) and IgA nephropathy (18.1%). Acute GN in resolution was found in 11.1% and minimal changes GN in 6.8% of cases. Most children with secondary GN had nephritis of Henoch-Schönlein purpura (HSP) (54.7%) and nephritis of systemic lupus erythematosus (SLE) (40.5%), while among hereditary GN Alport syndrome was most common (80.9%). In the group of children with primary GN who presented with nephrotic syndrome, most common forms were FSGS (38.5%) and MEPGN (24.0%). Minimal changes GN accounted for only 10.9% of cases. IgA nephropathy, primary or related to HSP (20.0%), FSGS (16.1%), MEPGN (12.6%) and Alport syndrome (9.7%) were the most common biopsy-proven renal diseases in Croatian children. The analysis provided data on the frequency of histological renal lesions in children in Croatia. The higher frequency of FSGS and MEPGN among Croatian children in comparison with other countries deserves further evaluation.

[Renal biopsy in children with isolated microhematuria]. / Biopsija bubrega u djece s izoliranom mikrohematurijom.

UNLABELLED: Isolated microscopic hematuria (IMH) in children always raises the question whether, besides other examinations, there is a need of performing a renal biopsy. Many authors consider IMH to be a minor abnormality where pathologic glomerular changes are not likely to be found, however, general agreement has not yet been achieved. The aim of the study was to evaluate the contribution of renal biopsy to the diagnosis of the disease in IMH. PATIENTS AND METHODS: Renal biopsy was performed in 54 children with IMH (22 boys and 32 girls, mean age 8.2 and 8.5 years, respectively) in whom urologic abnormalities, hypercalciuria, systemic diseases, coagulopathy or overt family history of renal disease were excluded. The mean duration of IMH prior to biopsy was 2.8 years. Biopsy specimens were examined by light (LM), immunofluorescent (IF) and electron microscopy (EM). RESULTS: Glomerular abnormalities were found in 43 (79.6%) patients. On LM 18 patients had normal glomeruli (NG), 22 mesangial proliferative glomerulonephritis (MEPGN), 9 focal glomerulosclerosis (FGS), 3 focal glomerulonephritis (FGN) and 2 membranoproliferative glomerulonephritis (MPGN). IF revealed 2 cases of NG, 5 cases of MEPGN, and all 3 cases of FGN as IgA nephropathy. EM detected GBM changes consistent with Alport syndrome in 21 patients, 7 of them with NG, 9 with MEPGN and 5 with FGS on LM. Diffuse thinning of GBM was found in 10 children, 7 with NG and 3 with MEPGN on LM. In 5 cases subepithelial hump-like deposits, which were considered to be the sign of acute postinfectious glomerulonephritis in resolution, were found. One of 2 cases of MPGN showed to be type II (DDD). On follow-up, 6 of 21 children with changes consistent with Alport syndrome developed clinical signs of the syndrome. Further surveillance is needed to confirm the significance of EM findings in others. CONCLUSION: The authors concluded that in children with IMH renal biopsy is justified and should always be analyzed by light, immunofluorescent and electron microscopy.