Collagenofibrotic glomerulopathy: clinicopathologic overview of a rare glomerular disease.

Collagenofibrotic glomerulopathy is an idiopathic glomerular disease characterized by massive accumulation of atypical type III collagen fibrils within the mesangial matrix and subendothelial space and marked increase in serum type III procollagen peptide levels. The disease is extremely rare, with most cases reported in Japan. The cause and pathogenesis are entirely elusive. Some cases were described in families; hence, a genetic mode of transmission, mostly by an autosomal recessive trait, has been assumed. Controversy exists about whether the glomerulopathy is a primary renal disease or manifestation of systemic disease. Proteinuria is a cardinal manifestation of this disease. Clinically, patients present with edema and hypertension and often progress to end-stage renal disease. A definite diagnosis can be established when typical histological findings are supported by immunohistochemistry for specific collagen types and electron microscopy with special staining methods. No specific treatment is available.