[Membranoproliferative glomerulonephritis. Morphological observations and considerations on pathogenesis]

Abstract

Membranoproliferative glomerulonephritis (MPGN) is a morphologically defined disease which can be subdivided into three types on the basis of different fine structural basement membrane changes. Type I (43%) is characterized by subendothelial deposits, essentially intact basement membranes, and normal C3 serum values on long term follow-up. Type II (32%), also known as dense deposit disease, is characterized by slight thickening of the basement membranes due to an electron dense, argyrophilic alteration of the basement membrane material the turnover of which seems to be disturbed. The carriers of this lesion can be recognized by persistently depressed serum C3 values. Type III (25%) is accepted by some working groups on the basis of mixed subendothelial and subepithelial deposits with discontinuity of the basement membrane, absence of classical intramembranous dense deposits but presence of a constant or inconstant serum C3 depression. The three types are demonstrated by light and electron micrographs of paediatric renal biopsies and discussed in detail with regard to different pathogenic mechanisms likely to be operative in different fine structural lesions (formation, removal and incorporation of deposits).