Diffuse thin glomerular basement membrane in association with idiopathic membranous glomerulonephritis.

Here we present a rare report of diffuse thin glomerular basement membrane (dTGBM) with idiopathic membranous glomerulonephritis (IMGN). dTGBM was found in 11 (2.04%) of 539 adult patients with IMGN. The male:female ratio was 1:1.2. Sixty patients with IMGN alone (matched for age and sex) were adjusted and analyzed as control patients. There was no significant difference in the clinical and laboratory data between the two groups except for the microhematuria, which was more frequently found in the dTGBM associated IMGN group (dTGBM + IMGN) (10/11, 91%) than in the IMGN group (19/60, 31.7%), and the difference was significant (p <0.001). However, no statistical difference was found in morphological parameters between the two groups except in the thickness of the glomerular basement membrane (GBM). In this study, using specific monoclonal antibodies against the chains of type IV collagen, no change in quality or location (in aberrant or no expression) was found in the collagenous composition of the dTGBM compared to the normal GBM. No prominent thickening or transformation of the GBM, which is characteristic for MGN, developed in the dTGBM + IMGN cases or IMGN. As a result, we could not detect any difference in the prognosis between these two groups. These findings support the view that IMGN can occur in patients with dTGBM, and the dTGBM patients may recover completely. The possible coexistence of these diseases was thus hypothesized due to the persisting microhematuria.