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.

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.