IgA vasculitis (Henoch-Schönlein purpura).

We report the first case of direct immunoflourescence-proven immunoglobulin A (IgA) vasculitis associated with influenza infection in an adult patient. IgA vasculitis, which was previously known as Henoch-Schönlein purpura, is the most common systemic vasculitis in children but rarely occurs in adults. Disease onset often occurs after upper respiratory tract infections that are caused by adenovirus or enterovirus. The American College of Rheumatology defines IgA vasculitis by the presence of any two of the following four criteria: age ≤ 20 years at disease onset, palpable purpura, acute abdominal pain, and a biopsy specimen that shows granulocytes in the walls of small arterioles or venules. Purpura, abdominal pain, and arthralgia comprise the classic triad. Renal involvement may be severe, especially in adults. Treatment is most often supportive but glucocorticoids and/or immunosuppressive agents are recommended in severe or refractory cases.