Medium-vessel vasculitis presenting as multiple leg ulcers after treatment with abatacept

Abatacept (Orencia) is a recombinant fusion protein of cytotoxic T-lymphocyte–associated antigen-4 and human immunoglobulin that inhibits T-cell activation and proliferation by binding to CD80 and CD86 on antigen-presenting cells and prevents binding to CD28 on T cells.1 The drug is approved by the US Food and Drug Administration to treat adult rheumatoid arthritis, juvenile idiopathic arthritis, and, more recently, psoriatic arthritis.