Adult Onset Immunoglobulin A (IgA) Vasculitis Secondary to Group A Streptococcus Infection.

Immunoglobulin A (IgA) vasculitis is a small blood vessel vasculitis that is mediated by immune complex deposition. While it is the most common cause of childhood vasculitis, the disease is uncommon in adults with variable clinical manifestations. A 65-year-old female presented with a diffuse erythematous, pruritic, painful rash across her legs, back, and arms of 12 days' duration. Associated symptoms included fatigue, lower extremity swelling, and migratory arthralgias of the knees and ankles. Skin examination revealed edematous, blanchable, erythematous, annular papules and plaques on the legs, back, and arms with pitting edema of the lower legs. Laboratory testing revealed an elevated erythrocyte sedimentation rate, hypoalbuminemia, proteinuria, hematuria, and a positive antistreptolysin O titer, indicative of recent group A infection. Treatment with systemic corticosteroids led to a resolution of all her symptoms. Adult onset IgA vasculitis differs in clinical manifestation and treatment from that of the pediatric population. This case demonstrates the importance of considering IgA vasculitis as a differential diagnosis in adults presenting with small vessel vasculitis.