IgA Vasculitis (Henoch-Schönlein Purpura)

Immunoglobulin A vasculitis (IgAV), formerly Henoch-Schönlein purpura, involves the small vessels of the joints, kidneys, gastrointestinal tract, and skin. IgAV can also affect the central nervous system and the lungs; however, these findings are rare. It is an acute IgA-mediated disorder typically self-limited and managed with supportive care; however, serious complications, such as renal failure, can occur. Henoch-Schönlein purpura is named after the German physician, Dr. Johann Schönlein and his student Eduard Henoch. Schönlein identified the association between joint pain and purpura, and Henoch identified gastrointestinal and renal involvement. Although Henoch-Schönlein purpura is named after Henoch and Schönlein, an English physician named William Heberden was the first to describe the disorder in the early 1800s. Iga vasculitis is now the preferred term due to a tendency toward etiology-based rather than eponym-based nomenclature. Of note, IgA vasculitis with nephritis has many overlapping features with IgA nephropathy, which is the most common glomerulonephritis in the world. The primary differences are that IgAV with nephritis is more likely to first occur in children younger than 15, while IgA nephropathy usually has an onset in patients older than 15. IgAV with nephritis is more likely to present with extrarenal symptoms; IgA nephropathy presents more often with gross hematuria. Histology in IgAV with nephritis shows more capillary staining and glomerular injury than in IgA nephropathy. Finally, IgAV with nephritis has a 98% clinical remission; comparatively, patients with IgA nephropathy progress to end-stage renal disease within 20 years of diagnosis in 30% to 50% of cases. Another interesting difference is that IgAV with nephritis presents more often during the winter "cold" season, while IgA nephropathy does not show seasonality. Much of the difference between the two disease processes results from IgAV being predominantly a disease of children and IgA nephropathy being primarily a disease of adults.