Efficacy of interferon in recurrent valaciclovir-refractory erythema multiforme in a patient not infected with hepatitis C virus.

Recurrent erythema multiforme (EM) is rare and is most typically related to infections with herpes simplex virus. Prophylactic administration of valaciclovir is the first-line treatment, but there is no agreement about second-line treatment in cases of ineffectiveness. We present a 31-year-old man who was not infected with hepatitis C virus (HCV), and had a history of severe and recurrent EM, unresponsive to valaciclovir, colchicine and hydroxychloroquine. The patient noticed that an intermittent flu-like illness seemed to have abrogated an EM flare. Because of this observation, the next EM flares were treated with short courses of interferon, which gave rapid and complete efficacy. Efficacy of interferon in EM has only been reported in two previous patients, in whom the drug was administered to treat HCV infection. Efficiency was attributed to treatment of the underlying HCV infection, which was thought to be the origin of EM in both cases. This is the first case, to our knowledge, reporting a dramatic response to interferon-alfa in a patient who was not infected with HCV.