Recurrent Erythema Annulare Centrifugum due to Influenza Type A.

Erythema annulare centrifugum (EAC) is a rare erythema characterized by erythematous and urticarial papules or annular plaques that enlarges centrifugally. The lesions usually involve the thighs and the legs. Several disorders are occasionally associated with EAC, infections, including mycoses, bacteria, or viruses and drugs have also been regarded as possible causes of this eruption. We present a 42-year-old dark-skinned woman affected by recurrent EAC that appeared secondary to influenza type A (H1N1). Histopathology showed a superficial form of EAC. In our case, a previous cytomegalovirus and Epstein-Barr virus (EBV) infection were identified and no underlying other diseases were found. Clarithromycin with calcipotriol betamethasone treatment was temporarily efficacious. In the last 3 years, the lesions started to appear every 2 weeks and tended to regress with local treatment after a variable period. We believe that the latent cytomegalovirus and the reactivity induced by EBV combined with influenza can determine, in our case, a cell mediate cutaneous immune response, which leads to the peculiar inflammatory disease known as EAC.