A possible association between influenza vaccination and small-vessel vasculitis.

We describe two patients who experienced small-vessel vasculitic syndromes after influenza immunization. Their illnesses were characterized by fever, arthralgias, and myalgias; uveitis and optic neuritis occurred in one patient, while the other had palpable purpura, which histologically was proved to be a cutaneous necrotizing venulitis. No viral or bacterial infection, medications, or underlying systemic rheumatic disease could be implicated. To our knowledge, small-vessel vasculitis occurring after influenza vaccination has not been previously reported.