Immunoglobulin A nephropathy (IgAN) is defined by the predominant deposition of IgA in the
glomerular mesangium. Light microscopic appearances and clinical features can vary
considerably, reflecting the many patterns of histopathologic injury seen in this
glomerulonephritis (GN) Closely associated with IgAN is Henoch-Schönlein purpura (HSP),
a smallvessel systemic vasculitis characterized by small blood vessel deposition of IgA
predominantly affecting the skin, joints, gut, and kidney. The nephritis of HSP is also …