P463: Pustular psoriasis induced by infliximab in a patient with Crohn's disease

Infliximab is a chimeric monoclonal antibody inducing potent anti-inflammatory responses by neutralizing biological activity of tumor necrosis factor (TNF)-α. It is widely used to treat various immune system-associated diseases such as Crohn's disease, rheumatoid arthritis, ankylosing spondylitis, psoriasis and psoriatic arthritis. However, infliximab can cause cutaneous adverse effects including erythema, urticaria, pruritus and lupus-like eruption. Rarely, it can provoke paradoxical aggravation or induction of psoriasis. A 28-year-old man with a history of Crohn's disease presented with erythematous scaly plaques with pustules on whole body which has lasted for a month. Punch biopsy was performed and histopathologic findings were consistent with pustular psoriasis. He had been treated with infliximab (10 mg/kg, intravenously) every 8 weeks for the past six years. We stopped using infliximab considering the possibility of paradoxical skin eruptions resulted from infliximab and most of the lesions showed complete regression. Though the exact pathophysiology of this paradoxical skin reaction is not clear, hypothesis has been suggested that a production of interferon-α is induced by dermal plasmacytoid dendritic cells and upregulated certain chemokine receptors provoke the migration and activation of T lymphocytes into the skin. Herein, we report an interesting case of pustular psoriasis paradoxically induced by infliximab.