Immunoglobulin A-Associated Vasculitis (IgAV) (Henoch-Schönlein Purpura) By Alexandra Villa-Forte, MD, MPH, Cleveland Clinic Reviewed / Revised Jun 2022 | Modified Sep 2022 View Patient Education Symptoms and Signs Diagnosis Treatment Key Points Topic Resources Immunoglobulin A-Associated.. Immunoglobulin A-Associated.. Immunoglobulin A-associated vasculitis (formerly called Henoch-Schönlein purpura) is vasculitis that affects primarily small vessels.