Collagenofibrotic glomerulopathy – A rare disease diagnosed with the aid of transmission electron microscopy

Collagenofibrotic glomerulopathy (CFG) is a rare idiopathic kidney disease characterized by abnormal deposition of atypical Type III collagen fibers in the glomerulus causing subendothelial and mesangial expansion, manifesting as progressive renal dysfunction accompanied by proteinuria. The majority of CFG cases reported in literature are from Japan where this disease entity was initially recognized. There is an increased awareness and diagnosis of this rare renal disease in India with the recent increase in utilization of electron microscopy (EM) in clinical diagnostic settings. We describe a 28-year-old Bangladeshi woman who presented with hypertension and nephrotic range proteinuria not amenable to treatment with steroids and cyclophosphamide, whose renal biopsy demonstrated diagnostic ultrastructural features of CFG. This illustrative case is presented to highlight the role of EM analysis for diagnostic accuracy in renal biopsy evaluation in addition to demonstrating the unusual renal biopsy findings of this rare entity.

Collagenofibrotic glomerulopathy- report of a rare renal disease with serial biopsies

@#Introduction: Collagenofibrotic glomerulopathy or collagen type-III glomerulopathy is a rare glomerular disease characterised by the deposition of type III collagen fibres in the subendothelial space and mesangium of the glomerulus. Case Report: Here, we present a case of collagenofibrotic glomerulopathy in a 49-year-old Indian female, the first to be reported from Singapore. Renal biopsy showed PAS (periodic acid-Schiff), silver and Congo red negative, amorphous extracellular material that expanded mesangial and subendothelial regions. Such materials were strongly positive for anti-collagen III immunofluorescent staining. Under electron microscopy, the mesangial and some subendothelial regions were greatly expanded by abundant collagen fibres which were different from normal collagen III fibres in both appearance and periodicity. Discussion: The availability of past renal biopsies for reference offered insight into disease progression. From the initial diagnosis of focal segmental glomerulosclerosis to eventually collagenofibrotic glomerulopathy over a time span of more than 10 years, this case highlights the gradual accumulation of collagen fibres in the glomeruli before classical features are apparent. It also emphasises the importance of electron microscopy in the diagnosis of this disease.

Type III collagen disorders: A case report and review of literature.

Collagen type III is a normal component of interstitium and blood vessels. Collagenofibrotic glomerulopathy (CG) and nail patella syndrome (NPS) are the diseases of abnormal type III collagen deposition. In spite of these curved frayed structures with a periodicity of 45–60 nm are deposited in subendothelium and mesangium in CG, they are found only in the basement membrane in NPS. The clinical features of CG are confined to the kidney, NPS has associated extra‑renal manifestations. Electron microscopy is essential to make the renal diagnosis in both these rare diseases. Both the entities considered to be systemic diseases evidence to suggest similar deposition in other organs, understanding etiopathogenesis and disease progression await research.