[Psoriasis as Koebner phenomenon in erythma migrans].

The Koebner phenomenon, described by Koebner in 1876, represents the appearance of isomorphic skin lesions in uninvolved skin in patients suffering from certain skin diseases. It can be induced by different mechanical, chemical, thermal and infectious stimuli. A 48 year-old woman developed an exacerbation of a latent psoriasis as a Koebner phenomenon in a migrating erythema caused by Borrelia afzelii infection.