Kidney Function

Membranous nephropathy (MN) is a pathologic entity characterized by a spectrum of changes in the glomerular basement membrane (GBM). Diagnostic features include subepithelial immune deposits and thickening of the GBM. In 1968, Ehrenreich and Churg proposed a morphologic classification of MN using electron microscopic findings. This classification was based on immune deposits in the GBM, GBM reaction to the deposits, and resolution of glomerular injury with resorption of the deposits. However, some biopsy specimens with features of MN also show spherical microparticles and podocyte microvillous entrapment in thickened GBM on electron microscopy. The presence of such features has been the source of considerable confusion. In this report, we describe an adult patient with the membranous pattern of injury using light microscopy and atypical electron microscopy findings. It is likely that this represents a distinct pathologic entity unrelated to classic membranous nephropathy.