A Rare Case of Diabetic Nephropathy and Type III Collagen Glomerulopathy

Collagenofibrotic glomerulopathy (CG) is a poorly understood kidney disease characterized by extensive deposition of abnormal type III collagen within the glomeruli. We report the case of a 25-year-old man with known type I diabetes mellitus who presented to the emergency department with diaphoresis, nephrotic-range proteinuria, hypertension, and elevated creatinine. Renal biopsy revealed combined collagenofibrotic glomerulopathy and diabetic nephropathy. This case highlights the clinicopathological features of type III collagen glomerulopathy and its possible association with diabetic nephropathy.

Collagenofibrotic Glomerulopathy

Collagenofibrotic glomerulopathy or LMX1B-associated nephropathy is a rare disease in which type III collagen accumulates in the glomeruli. We herein report a 64-year-old Japanese woman with an elevated serum creatinine level and persistent proteinuria for 7 years. An electron microscopic study using tannic acid showed curved and frayed collagen fibers within mesangial and subendothelial regions compatible with type III collagen depositions. The distribution of type IV collagen α1-6 chains was normal. Since no pathogenic mutations were identified in the LMX1B gene, she was diagnosed with collagenofibrotic glomerulopathy and treated with angiotensin II receptor blocker and calcium antagonist to control her blood pressure.

Diagnosis of Collagen Type III Glomerulopathy Using Picrosirius Red and PASH/Masson's Trichrome Stain

Canine collagen type III glomerulopathy (Col3GP) is a rare juvenile nephropathy in which irregular type III collagen fibrils and fibronectin accumulate in glomerular capillary walls and the mesangium. Necropsy findings were reviewed from 5 puppies diagnosed with Col3GP at 6 to 18 weeks of age. Histologically, with hematoxylin and eosin stain, the glomerular capillary walls and mesangium were diffusely and globally expanded by homogeneous pale eosinophilic material. Ultrastructurally, the subendothelial zone and mesangium were expanded by fibronectin and cross-banded collagen type III fibrils, diagnostic of Col3GP. Two additional stains were employed to identify the material within glomeruli as fibrillar collagen using light microscopy. In all 5 cases, the material was red with picrosirius red and birefringent under polarized light, and was blue with periodic acid-Schiff/hematoxylin/trichrome (PASH/TRI), thereby identifying it as fibrillar collagen. Based on these unique staining characteristics with picrosirius red and PASH/TRI, Col3GP may be reliably diagnosed with light microscopy alone.

Collagenofibrotic glomerulopathy

Background

Collagenofibrotic glomerulopathy is a rare renal disease of unknown etiology that is secondary to deposition of type III collagen within the glomerulus. Only rare case series exist in the literature.

Methods

Renal biopsies diagnosed with collagenofibrotic glomerulopathy were prospectively collected at the Center for Renal and Urological Pathology (AAK) (Chennai, Tamil Nadu, India) from 2012 to 2015. Eight patients were entered into the study. The average age was 38 years with five males and three females.

Results

All patients presented with nephrotic syndrome, and five displayed hypertension. The average serum creatinine was 146.5 µmol/L (88.4–282.9 µmol/L range). All serologic testing was negative, and complement levels were normal. No clinical evidence of nail–patella syndrome was seen. All cases showed diffuse mesangial expansion and double contour formation by peroidic acid-Schiff (PAS)-negative material. All immunofluorescence studies were negative. By electron microscopy all cases showed electron dense, banded to curvilinear collagen bundles within the mesangium and subendothelial aspect of the peripheral capillary walls. All patients appear to have sporadic disease occurrence with no family history of renal disease. No hemolytic uremic syndrome, liver fibrosis, lymphoma or co-occurrence of other renal disease were seen.

Conclusion

Collagenofibrotic glomerulopathy is a rare disease that appears to occur more frequently in adult Indian populations in a sporadic, non-familial manner. To our knowledge, this is the largest cases series of collagenofibrotic glomerulopathy in an adult population.

Collagenofibrotic glomerulopathy-a review

Collagenofibrotic glomerulopathy (CG) is a rare cause of idiopathic nephrotic syndrome characterized by massive accumulation of atypical Type III collagen fibrils within the mesangial matrix and subendothelial space of the glomeruli. A definite diagnosis can be established when typical histological findings are supported by electron microscopy. This disease exhibits indolent progression and as yet has no specific treatment. The present article reviews the clinicopathological features, epidemiology and proposed mechanisms of pathogenesis of CG. A search of the English language literature identified 38 cases of CG, of which 22 are reported from Asian countries. An additional three cases are being reported from this Institute in India and are illustrated herein. These reports contribute to a better understanding of this disease, which although not as prevalent, should be considered as a differential diagnosis in cases of mesangiocapillary form of glomerular injury.