IgA nephropathy with podocytic infolding glomerulopathy

Dear Editor,Podocytic infolding glomerulopathy(PIG)is a glomerular disease characterized by specific structures of the thickened glomerular basement membrane(GBM),including microspheres,microtubular structures,and podocytic infolding.It was first reported in 1992 by Sato et al.I This type of glomerulopathy has not been included in the World Health Organization's classification of glomerular diseases.The concept of PIG was then proposed in 2008 by the Japanese Society of Nephrology according to electron microscopic findings from renal biopsies of 25 patients in Japan.The diagnostic criteria included nonargyrophilic holes in the GBM by light microscopy and microspheres and/or microtubules of 50-150 nm within the GBM by electron microscopy.PIG is divided into three types:type A with only primary podocytic infolding,Type B with both primary podocytic infolding and microstructures in the GBM,and type C with only microstructures in the GBM.?Some studies on pathogenic mechanisms suggest a potential association with complement activation.