Glomerular membranopathy in children with IgA nephropathy and Henoch Schonlein purpura

We evaluated renal biopsies from 34 children with IgA nephropathy or Henoch Schonlein purpura to further characterize the ultrastructural features of the glomerular membranopathy that occurs in these disorders. Focal glomerul ar basement membrane damage was identified in 29 children and was severe in 4 of the children. Alterations included focal and segmental attenuation, s plitting, duplications, and spike-like subepithelial protrusions of the lam ina densa, along with saccular glomerular microaneurysms arising at the par amesangium. Those cases with extensive glomerular basement membrane lesions had either moderate or severe glomerular alterations apparent by light mic roscopy. Over half of the cases with glomerular membranopathy had immunohis tological or ultrastructural evidence of focal peripheral glomerular capill ary wall immune deposits and electron-dense deposits occurred at sites of g lomerular basement membrane splitting. Despite the focal attenuation of the glomerular basement membrane, we did not identify any biopsy with findings of thin basement membrane disease. The glomerular basement membrane ultras tructural findings we describe are characteristic of IgA nephropathy and He noch Schonlein purpura, are common in children with these disorders, and ar e similar to the ultrastructural alterations of the basement membrane that occur in other glomerulonephritides. These basement membrane injuries may b e inflammatory cell or immune mediated but their pathogenesis requires furt her study.