Collagenofibrotic glomerulonephropathy associated with immune complex deposits

A 66-year-old Japanese male, who suffered from persistent proteinuria and leg edema, underwent renal biopsy. Light microscopy revealed marked narrowing of the glomerular capillary lumen with a diffuse accumulation of weakly PAS-positive material. By electron microscopy, abundant abnormal collagen fibers were observed predominantly in the subendothelial space and occasionally in the mesangial matrix, The fibers had a periodicity of about 60 nm and were immunoreactive for anti-type III collagen. Subendothelial electron-dense deposits were also found in some of the capillary walls. The serum level of procollagen III peptides was elevated and changed in parallel with the amount of proteinuria during the patient's clinical course. On the basis of these findings, a diagnosis of the collagenofibrotic glomerulonephropathy was made. A review of the literature, including 29 similar or identical cases, failed to reveal the etiology and pathogenesis of this disease. We suggest that this disease may be divided into two different clinical subtypes, an adult-onset type and a pediatric type.