Reversible Henoch-Schönlein purpura complicating adalimumab therapy

The tumour necrosis factor antagonists have demonstrated efficacy in the induction of remission and its maintenance in numerous chronic inflammatory conditions. These agents are generally well tolerated but with the increasing number of patients receiving anti-tumour necrosis factor-α (anti-TNFα) therapy, more adverse reactions are expected to occur. Cutaneous eruptions complicating treatment with anti-TNFα agents are common, occurring in around 20% of patients. Most reactions are mild-to-moderate and rarely warrant treatment withdrawal. We herein present a case of Henoch-Shönlein purpura (HSP) vasculitis following treatment with the monoclonal anti-TNFα antibody adalimumab for ileo-colic Crohn's disease. The reaction occurred after 18 months of adalimumab therapy and discontinuation of the anti-TNFα resulted in rapid improvement of the condition. The causal relationship has become even more likely when the purpura reappeared after restarting adalimumab. The patient started infliximab, with disease control and no cutaneous side effects. To the best of our knowledge, this is the second case report of HSP complicating adalimumab therapy. Although adalimumab is theoretically less related to immune-mediated reactions, clinicians must be aware that adverse side effects may still occur. This is the first case that shows that infliximab can be safely used in patients with adalimumab related HSP. We discuss the literature and potential causal mechanisms and propose possible approaches to its management.