Author: Arcana Luo, Medical Student, University of Auckland, New Zealand; Chief Editor: Dr Amanda Oakley, Dermatologist, Hamilton, New Zealand, March 2014.
The Koebner phenomenon describes the appearance of new skin lesions on areas of cutaneous injury in otherwise healthy skin. It is also known as the isomorphic response.
Lesions arising through the Koebner phenomenon:
Lesions may form in patients with or without pre-existing skin conditions. A true Koebner response can be confirmed by experimentally reproducing lesions with different methods of injury. However this may not always work and is not usually practical or desirable.
Koebner phenomenon lesions are often linear in shape, as they follow the route of cutaneous injury. Aside from linear skin injury, linear lesions arising from the Koebner phenomenon can also be seen in mosaic skin disorders (eg segmental lichen planus).
Patients differ in terms of how intensely they respond to skin injury.
Patients who develop Koebner phenomenon in response to one method of injury are susceptible to other triggering stimuli. This is particularly noted in patients with psoriasis. Conversely, a patient who does not develop skin lesions with one type of injury is not expected to exhibit Koebner phenomenon with another type of injury.
The time from injury to formation of a skin lesion depends on the specific skin disease. For psoriatic lesions (these are known as plaques), it is between 10 to 20 days, with a range from 3 days to 2 years. The time to lesion formation can differ in the same patient.
Some reports suggest the Koebner phenomenon may affect other surfaces apart from the skin, such as the oral mucosa, or cause lesions in internal organs, such as the lungs after damage from chronic infection. It is uncertain whether it occurs in systemic diseases such as sarcoidosis and systemic lupus erythematosus. Cutaneous lesions due to Koebner phenomenon have been reported in these diseases.
Other phenomena in relation to trauma or skin damage are distinct from the Koebner phenomenon.
True Koebner response
Occasional, localised traumatic lesions
A variety of skin injuries have been found to trigger the Koebner phenomenon.
Diseases/ medical conditions
The cause of the Koebner phenomenon is unclear. Current theories suggest the Koebner phenomenon requires both epidermis and dermis to be injured at the same site. The production of inflammatory substances and neuropeptides has been postulated as a non-specific first step, triggering a secondary disease-specific process. The role of chemical messengers such as nerve growth factor (NGF) may be important and is being investigated.
Psoriasis is the most-researched condition that exhibits the Koebner phenomenon, and can be used to aid diagnosis.
Koebner phenomenon has been noted to be particularly prevalent in:
Other studies indicate that Koebner phenomenon:
Plaques exhibiting the Koebner phenomenon can appear on any area of the body, even those not usually involved by psoriasis.
In recalcitrant psoriasis, a concurrent skin condition such as contact dermatitis may drive the disease via the Koebner phenomenon.
Although it is not possible to prevent all cutaneous injury, if you are susceptible to the Koebner phenomenon, take care to avoid:
The following things have been experimentally suggested to prevent the Koebner phenomenon:
Treatment for cutaneous lesions arising from the Koebner phenomenon depends on the associated skin condition.
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