Introduction:
Glomerular fibrillary deposits in diabetic nephropathy (DN) are poorly understood. This ultrastructural study using electron microscopy aims to elucidate the characteristics of mesangial fibrillary deposits and their clinical correlation in patients with DN.
Methods:
We conducted a retrospective study on renal biopsies performed between May 2016 and May 2022 at a tertiary care center in South India. Biopsies were evaluated using light microscopy, immunofluorescence, and electron microscopy. Clinical data and renal biopsy features were reviewed.
Results:
Diabetic fibrillosis was identified in 39 of 3,124 biopsies (1.24%). The mean age was 48.35 ± 11.24 years, with a male predominance (87.17%). All patients had diabetes mellitus, with 74.35% also having hypertension. Clinical presentations varied; 25.64% had nephrotic syndrome (mean proteinuria 6.40 ± 2.88 g/dl), and 66.6% exhibited renal dysfunction (mean serum creatinine 4.04 ± 3.42 mg/dl; mean proteinuria 3.1 ± 2.96 g/dl). Immunofluorescence revealed an absence of immune deposits. Light microscopy classified patients into DN Class III (61.53%), Class IV (23.07%), and Class II (15.38%). Electron microscopy uniformly showed mesangial widening with random, non-branching fibrils (9–15 nm in diameter). The mean GBM thickness was 811.55 ± 226.55 nm in nephrotic syndrome and 767.87 ± 278.58 nm in renal dysfunction cases. Notably, 30.76% displayed type C podocyte infolding glomerulopathy, with subepithelial microspherules.
Conclusions:
Diabetic fibrillosis is a rare form of DN characterized by non-immune mesangial fibrils. Its occurrence, without association with other glomerular diseases in diabetes, suggests it may be a distinctive marker of diabetic kidney disease. Further research is necessary to understand its pathogenesis and clinical implications.
I have no potential conflict of interest to disclose.
I did not use generative AI and AI-assisted technologies in the writing process.