Koebner Phenomenon

What it means

The appearance of new skin lesions on previously unaffected skin secondary to trauma. This phenomenon is also termed the isomorphic (from Greek, equal shape) response, given the fact that the new lesions that appear are clinically and histologically identical to the patient's underlying cutaneous disease.

The Koebner phenomenon is typically associated with preexisting skin disease. Clinical entities that commonly display the Koebner phenomenon include psoriasis, vitiligo, lichen planus. The incidence of Koebnerization ranges broadly within these entities; estimates of the prevalence of the Koebner phenomenon are approximately 11 to 75% in psoriasis and 21 to 62% in vitiligo.

Rare diseases that can present with this1

The range is how often this sign appears among people diagnosed with each disease — it is not a probability of having any of them. Many of these signs also occur in common, non-rare conditions. A sign on this page is a conversation to have with a clinician, not a conclusion.

Part of the broader category