The Koebner phenomenon or isomorphic response was originally described in p
soriasis and has subsequently been observed in various other diseases. We r
eport a patient with isomorphic response in scleromyxoedema, a variant of p
apular mucinosis with diffuse infiltration of the skin. The Koebner phenome
non was due to a scratch test performed 4 weeks before the appearance of st
reaky, lichenoid infiltrations on the forearms.