Henoch Schonlein Purpura is a small vessel vasculitis characterized by palpable purpura, ahralgia, gastrointestinal signs and symptoms and glomerulonephritis. Patients have a normal platelet count, other laboratory findings includes mild leukocytosis, occasional eosinophilia, normal serum complement and elevated IgA. Reference: Harrison's Principles of Internal Medicine 18th edition, chapter 326.