Histopathological and electron microscopic spectrum of glomerular diseases in pediatric and adult patients with nephrotic range proteinuria and nephrotic syndrome: A tertiary center study

Objectives: Nephrotic range proteinuria (NRP) and nephrotic syndrome (NS) are common manifestations of glomerular diseases across age groups. Kidney biopsy remains the gold standard for diagnosis. However, in resource-limited settings, the availability of electron microscopy (EM) is restricted, necessitating evaluation of its diagnostic utility. This study aims to assess the histopathological spectrum of glomerular diseases in pediatric and adult patients presenting with NS and NRP, and to evaluate the diagnostic utility of EM. Methods: A total of 180 consecutive renal biopsies were analyzed according to the 2016 Renal Pathology Society Consensus guidelines. Results: Of the 180 patients, 36 (20%) were pediatric and 144 (80%) were adult. NS was more common in children (72.2%), while nephrotic-range proteinuria (NRP) without full-blown NS predominated among adults (52.8%). In pediatric patients with NS, the most frequent diagnosis was minimal change nephropathy (MCN) (38.5%), followed by focal segmental glomerulosclerosis (FSGS) (19.2%). Among pediatric NRP cases, MCN remained the most common (27.7%), with lupus nephritis (22.3%) and FSGS (16.6%) also notable. In adults with NRP, the leading diagnosis was FSGS (27.1%), followed by IgA nephropathy, membranous nephropathy (MN), and amyloidosis, each accounting for 11.8% of this subgroup. Among adults with NS, FSGS remained predominant (26.5%), followed by amyloidosis (17.6%) and MN (14.7%). EM contributed to diagnosis in 29.4% of all cases ( n = 53), being essential for diagnosis in 12.2% and supportive in 17.2%. EM was particularly crucial in identifying lupus podocytopathy, dense deposit disease, Alport syndrome, and early-stage MN, which may not be definitively diagnosed by light or immunofluorescence microscopy alone. Conclusion: FSGS and MCN are the most common causes of NS across age groups. The findings highlight a shifting spectrum of glomerular diseases, consistent with national and global trends. Although not routinely feasible, EM provides significant diagnostic value in selected cases. Preserving tissue for potential EM evaluation is strongly recommended, especially in ambiguous or complex presentations.