Lupus and nonlupus membranous glomerulopathy. Quantitative comparison of the subepithelial deposits and glomerular basement membrane including clinicomorphologic correlations.

Abstract

We examined quantitatively 11 renal biopsy specimens from patients with class Va WHO lupus membranous glomerulopathy (LMGN) and 16 from patients with primary (nonlupus) membranous glomerulopathy (NLMGN) for whom both light and electron microscopy as well as immunofluorescence microscopy and full clinical data were available and compared these specimens with six cases of normal controls. In LMGN, subepithelial deposits resembled those seen in stage III of membranous glomerulopathy (MGN) according to the scheme proposed by Churg's group, i.e., for the present study only advanced cases of NLMGN (stage III according to this scheme) were selected. The electron micrographs were scanned in Primax flatbed A4 scanner and morphometric investigations were then performed by means of a computer image analysis system to compare glomerular basement membrane (GBM) thickness and the electron-microscopic density of the deposits in LMGN and NLMGN as well as to study whether these parameters could correlate with the clinical data. The study revealed that in LMGN the GBM thickness and the electron-microscopic density of the deposits were significantly increased in comparison with NLMGN. It should also be noted that both in LMGN and NLMGN groups the degree of proteinuria was closely correlated with the density of the deposits, but not with the GBM thickness. Moreover, no correlations were found between serum creatinine and the GBM thickness as well as between serum creatinine and the density of the deposits in these groups. In conclusion, the present data confirm that in LMGN and NLMGN proteinuria mainly depends on density of the subepithelial deposits. Furthermore, in cases with especially high density of these deposits systemic lupus erythematosus (SLE) should be taken into consideration, even if this etiology was not clinically suggested at the time of biopsy.