The Koebner Phenomenon

To the Editor.— In his article in the July 1981Archives(117:415) on the Koebner phenomenon, Waisman states that an "essential feature of the reaction is . . . that the isomorphic response evolves in a patient with psoriasis when the disease is in a reactive phase,. . . or on the `upswing.' " It may be true that patients in the acute state are more susceptible to having the Koebner reaction develop, but, in our experience, most cases occur in chronic, stable, plaque-type psoriasis.