Landscape of kidney biopsy diagnoses in a Romanian pediatric cohort

BACKGROUND: There is relatively little information available on the landscape of histological findings in kidney biopsies of pediatric populations, particularly in Eastern Europe. METHODS: Records of pediatric native kidney biopsies processed between 1996 and 2023 were extracted from the registry of the Victor Babeş National Institute of Pathology, Bucharest. Demographic characteristics, biopsy indications and histopathological findings, as well as temporal trends thereof, were analyzed and compared to those reported in other European studies. RESULTS: A total of 326 native pediatric kidney biopsy records were identified. The most common biopsy indications were urinary abnormalities (32.8%) and nephrotic syndrome (30.4%). A clinical systemic lupus erythematosus (SLE) diagnosis constituted the main biopsy indication in 17.8% of cases, among which we identified 17 patients with no overt renal involvement, in whom kidney lesions were nonetheless found upon biopsy for all but one. The most frequent histopathological diagnoses overall were: lupus nephritis (LN; 17.8%), minimal change disease (MCD; 16.3%), IgA nephropathy (including IgA vasculitis; 14.1%), Alport syndrome/thin basement membrane disease (Alport/TBMD; 11.3%) and focal segmental glomerulosclerosis (6.7%). LN and MCD frequencies increased over time, while Alport/TBMD frequencies decreased. CONCLUSIONS: This study addresses an important gap in the landscape of pediatric biopsy-proven kidney diseases in Europe. While our results largely mirror those reported in other European studies, one important difference lies in the high proportion and increasing trend of LN cases, driven by shifts in local practices towards more accurate assessment of SLE patients, to obtain histopathological evaluation and classification of LN in its earliest stages.