Collagenofibrotic glomerulopathy

Abstract

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.

Keywords: collagenofibrotic glomerulopathy; primary glomerular fibrosis; type III collagen glomerulopathy.

Fig. 1.

Morphology of collagenofibrotic glomerulopathy. (A) Global mesangial expansion and focal double contour formation (H&E stain, ×400 original magnification). (B) Mesangial expansion and peripheral capillary loop double contour formation staining a variegated blue on Masson trichrome stain (×200 original magnification). (C) Jones silver stain showing loss of silver staining within the expanded mesangium and peripheral capillary loop double contours (×400 original magnification). (D) Type III collagen immunohistochemical stain showing staining of the peripheral capillary loops and mesangium (×600 original magnification).

Fig. 2.

Electron microscopic findings in collagenofibrotic glomerulopathy. (A) Peripheral capillary loop with expanded subendothelial space containing stacked collagen bundles (×10 000 original magnification). (B) Curvilinear collagen fibrils (arrows) with frayed ends consistent with type III collagen (×20 000 original magnification). (C) Curvilinear collagen fibrils forming stacks (arrows) consistent with type III collagen (×20 000 original magnification). (D) Curvilinear collagen with frayed ends (arrow) show frequent arrangement into dense stacks (arrowhead) (×30 0000 original magnification).