What Is Koebner’s Phenomenon?

Koebner’s phenomenon (pronounced KOHB-nurs) is a skin condition that occurs after skin trauma. The condition is named after Heinrich Koebner, the scientist who discovered it in 1876.

Koebner's is often experienced by people with skin conditions like psoriasis, vitiligo, and lichen planus.

This article will help you understand what Koebner's phenomenon is, how to avoid it, and how to treat it if you have it.

What Is Koebner’s Phenomenon?

Koebner’s phenomenon (also called an isomorphic response or Koebnerization) is a psoriatic rash that appears around an injury, such as a cut or a burn. The rash can show up anywhere on the body where trauma to the skin has occurred. 

Koebner's phenomenon looks like raised skin lesions. The lesions tend to have the same features as a person’s existing dermatologic condition. The lesions usually follow the injury lines, and they may cover the entire skin injury or develop on only one part.

People with preexisting skin conditions are most susceptible to Koebner’s phenomenon. For example, Koebnerization occurs 11% to 75% of the time in people with psoriasis and 21% to 62% of the time in people with vitiligo.

Psoriasis

Psoriasis is an autoimmune disorder in which the body attacks normal skin cells. There are many types of psoriasis, all of which affect the body in different ways:

• Plaque psoriasis is most commonly found on the elbows, scalp, knees, and back. The lesions are red, raised, and scaly, and they tend to crack, bleed, and itch.
• Guttate psoriasis usually affects children and young adults. The condition is usually triggered by a viral or bacterial infection. The lesions are small, pink, tear-shaped, and scaly.
• Inverse psoriasis is an uncommon type that tends to affect people with excess weight or obesity. The lesions typically appear in skin folds, such as armpits, under the breasts, between the buttocks, in skin folds of the genitals, or on the belly.
• Pustular psoriasis appears with pus-filled blisters that eventually turn to crusty patches of skin. It is often triggered by certain medications or infections.
• Scalp psoriasis can appear on the head, ears, and neck. The rash is red, thick, scaly, and extremely itchy. Sometimes it can be mistaken for dandruff.
• Nail psoriasis may result in pitting or crumbling of the nail plate and black, white, or yellow spotting on the nails. 
• Erythrodermic psoriasis is a severe form of plaque psoriasis that affects the whole body and causes the skin to peel off in large sheets. The condition can lead to dehydration and infection and, if not treated promptly, can be fatal.

Psoriasis flares are often triggered by medications, illnesses, or infections. While the exact cause of Koebner’s phenomenon remains unclear, it is believed that skin injuries may trigger psoriatic flares. 

Vitiligo

Vitiligo is an autoimmune condition where skin pigmentation is lost, resulting in smooth white patches on the body. People with vitiligo may also experience early graying of their hair and itching on the affected skin regions. 

Like psoriasis, vitiligo has certain triggers, including stress, sunburn, chemicals, and viruses. Skin injuries can also trigger Koebnerization.

Studies have shown that Kobernization is more likely to occur when vitiligo covers a larger amount of the body's surface area as well as when disease activity is greater.

Lichen Planus

Lichen planus is an autoimmune disease that causes a purple, itchy rash. The condition can affect many parts of the body, including the inside of the mouth. 

Koebner’s phenomenon is believed to be an activation of an underlying disease, and lichen planus is an autoimmune disease that may trigger it.  

Causes

The exact cause of Koebner’s phenomenon is not known. However, theories suggest that it is triggered by an abnormal immune response (that is, it is immune-mediated).

In addition, some experts believe that both the epidermis and dermis of the skin must be injured for the condition to be triggered.

If a person has an existing autoimmune disease, Koebner’s can be brought on by damage to the skin. Examples of trauma that may bring on Koebner’s phenomenon include:

• Animal or insect bites
• Sunburn or other burn injuries
• Friction (including from shaving)
• Cuts
• Freezing
• Pressure
• Tattoos
• Some vaccines
• Tuberculosis test
• Iodine

Body Modifications

Tattoos and piercings may lead to Koebner’s phenomenon in people with preexisting autoimmune skin conditions because tattoos and piercings, while added to decorate and beautify the body, also injure the skin (which is a risk factor for developing Koebner’s phenomenon).

In a study of tattoo-induced Koebner’s, 82% of participants said that their tattoo positively affected their body image. The study concluded that tattooing should not be a contraindication for people with psoriasis but that they should receive proper counseling beforehand.

Seeing a Dermatologist

If you notice changes in your skin, make an appointment with a dermatologist. If you notice lesions on a skin injury—especially if you have an autoimmune disease like psoriasis—a dermatologist will be able to screen for and treat Koebner’s phenomenon.

Koebner’s phenomenon is diagnosed by looking at the lesions, which behave in the same way as a person’s preexisting skin condition. A dermatologist will also rule out an infection or allergic reaction.

If Koebner's is diagnosed, the treatment usually includes either systemic treatment of psoriasis to suppress Koebner’s phenomenon or topical creams, lotions, and ointments (both over-the-counter and prescription) to cover the lesions.

Skin Care for Psoriasis Flare-Ups

Psoriasis flare-ups can be brought on by many things, including stress, skin trauma, dry skin, medications, alcohol, and infections.

When you experience flare-ups, there are some things your dermatologist may prescribe to calm and heal your skin:

• Topicals such as steroid creams, nonsteroid creams, and over-the-counter (OTC) creams, shampoos, and soaps to heal and soothe the skin
• Phototherapy (light therapy), which uses ultraviolet light to slow the growth of affected skin cells
• Systemic injectable or oral medication that works throughout the body
• Diet and lifestyle changes, which can include maintaining a weight that's healthy for you and trying to reduce your stress

You can often treat mild flares at home. The National Psoriasis Foundation suggests using:

• Aloe vera
• Diluted apple cider vinegar
• Dead sea salts in a warm bath
• Oat paste or bathing in oats (to relieve itch)
• Tea tree oil
• Tumeric in supplement form

Frequently Asked Questions

What does Koebner’s phenomenon look like?

The appearance of Koebner’s phenomenon depends on which autoimmune condition a person has. Koebner’s phenomenon tends to present in the same way as the preexisting condition.

For instance, if a person has psoriasis, Koebner’s would present as a raised, itchy, flaky rash that runs over the skin injury. 

What is an isomorphic response?

An isomorphic response is another term for Koebner’s phenomenon. Isomorphic is Greek for “equal shape.” The phrase is used because the lesions from Koebner’s are identical to a person’s underlying condition.

How can I prevent psoriasis flare-ups?

Psoriasis tends to flare up if a person encounters specific triggers. Triggers are different for every person. Common triggers include stress, skin trauma, dry skin, medications, alcohol, and infections.

Identifying the things that tend to trigger your psoriasis and avoiding them is important, but it might take some detective work. A symptom journal may help you figure out what causes your flare-ups.

A Word From Verywell

If you have psoriasis or another autoimmune disease of the skin, you might be at increased risk of developing Koebner’s phenomenon.

If you have an injury to your skin, including those from tattoos and piercings, watch your injury closely for lesions. If any changes develop, contact your doctor or dermatologist.