What is the Koebner phenomenon?

The Koebner phenomenon is an aspect of psoriasis that’s well-known but not completely understood. It describes the formation of psoriatic skin lesions on parts of the body that aren’t typically where a person with psoriasis experiences lesions. This is also known as an isomorphic response.

The condition is named after the dermatologist Heinrich Koebner. He was the first to observe this condition in the 19thcentury.

Psoriasis is a chronic autoimmune disease that affects the skin. If you have psoriasis, your body’s immune system acts abnormally and attacks otherwise healthy skin. In the case of psoriasis, new skin cells are produced at a rate that’s too rapid. These cells push their way onto the skin’s surface and leave dry, scaly, and often painful patches.

These patches or lesions tend to flare up when there are triggers, such as psychological stress or traumatic injury to the skin. Lesions can appear anywhere on the body. They most often occur on the:

  • scalp
  • knees
  • elbows
  • lower back

If you have psoriasis, you most likely experience repeated flare-ups in the same areas.

Koebner noted that some people with psoriasis developed lesions in areas in which the skin had been traumatized. This could be from a cut, a bruise, or a burn. Lesions may also develop on parts of the body where the skin is irritated by a waistband, belt buckle, or bra strap.

In all these cases, the lesions appeared in areas outside of the usual spots affected by psoriasis.

Scientists have also identified a condition in which surface skin injuries or trauma trigger more profound responses than lesions. In some cases, skin damage can lead to psoriatic arthritis.

Unlike osteoarthritis, which results from wear and tear on the joints, psoriatic arthritis is an autoimmune disease. Healthy tissue in the joints of people with psoriasis is attacked by an overactive immune system. This can result in pain, stiffness, and inflammation in the affected joint.

The development of the psoriatic arthritis following surface injury is sometimes referred to as deep Koebner phenomenon.

The symptoms of Koebner phenomenon are treated the same way as psoriasis and psoriatic arthritis are treated. If you experience symptoms, you should consult a dermatologist who specializes in treating psoriasis. For skin lesions, they may recommend topical medications, ultraviolet light therapy, or oral medications.

Psoriatic arthritis is usually treated with a combination of medications. Mild cases may only require nonsteroidal anti-inflammatory drugs (NSAIDs). If you have a more serious case, you might need drugs that suppress the immune system.

Your dermatologist could suggest steroid injections be made directly into the affected joint, which will reduce inflammation and other symptoms. If the damage has been too great, you may need a joint replacement.

If you notice scaly patches of skin, you should have them diagnosed by a dermatologist. There are several other conditions that leave dry patches of skin, such as eczema or seborrhea. Getting a confirmed diagnosis will help make sure you get the best treatment.

If you know you have psoriasis, talk with your dermatologist about Koebner phenomenon and what you can do to help minimize your odds of experiencing it. The advice may be as simple as treating your existing psoriasis to the best of your ability and protecting your skin in every way possible.

Be sure to pay attention to skin that comes in contact with your waistband or bra or other clothing that might irritate it. The earlier you can spot the signs, the earlier it can be treated, and the sooner you can find relief.

There’s no way to predict who will develop this condition, but having psoriasis is the key risk factor. In general, people with psoriasis are advised to take greater care of their skin than the general public. Taking care of your skin means the following:

  • Don’t spend a lot of time in the sun, and keep your skin moist.
  • Use a moisturizer and a humidifier if you live in an area with especially low humidity.
  • Try to avoid bruising or cutting your skin.
  • Keep your scalp clean, and use tar shampoos if your doctor recommends it.
  • Leave lesions alone unless you’re applying a topical medication. Don’t pick or scratch lesions, as this can make flare-ups worse.