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Can Scratches Become Flares?

Updated on March 18, 2021
Medically reviewed by
Ariel D. Teitel, M.D., M.B.A.
Article written by
Erik Linklater, Ph.D.

Do your scratches, sunburns, insect bites, or tattoos become scaly patches after they’ve healed? For some people with psoriasis, skin injury can cause psoriasis symptoms in the affected area. This is known as the Koebner phenomenon, and it occurs in about 25 percent of people with psoriasis. It also induces multiple types of psoriasis.

“I get psoriasis wherever I cut myself,” reported one MyPsoriasisTeam member. “Ingrown hair, scrapes, or pimples all become new plaque psoriasis spots on me,” shared another.

What Is the Koebner Phenomenon?

The Koebner phenomenon is the appearance of new psoriasis lesions on previously unaffected areas of skin. A psoriasis flare will develop where the skin has been injured, whether through a scratch, burn, tattoo, or bug bite. The Koebner phenomenon is often referred to as Koebnerizing or Koebnerization.

“Once the skin heals, a new patch [of psoriasis] will usually arrive in its place,” explained one member.

Flare-ups can occur in areas not typically prone to common triggers, some members say: “My psoriasis appears in some unusual places, all of which are areas of repeated pressure. I also get rashes where my lip and nose are pierced.” “Tongue, too,” shared one member.

Other forms of skin irritation can lead to Koebner flare-ups as well. For example, there have been at least two recent case reports that document the Koebner phenomenon being triggered near the ears by wearing face masks during the COVID-19 pandemic. And one member experienced Koebnerization from hair removal. “My mistake was waxing — psoriasis pops up anywhere the skin has been injured. I should have known better. Now I'm stuck with awful-looking legs.”

What Causes the Koebner Phenomenon?

It is well known that psoriasis is caused in part by a misfiring of the immune system, and both immune cells and skin cells can factor into the formation of psoriatic lesions. It is not fully understood why flare-ups happen after an injury, however.

During the past several years, a great deal of research has expanded our knowledge of psoriasis and the Koebner phenomenon, with much of this research focusing on molecules involved in inflammation, including molecules called IL-17, IL-6, and CCL20.

IL-17 (IL stands for interleukin) is known to be one of the key molecules that drives psoriasis. IL‐17 starts the process of wound repair that leads to the build-up of excess skin layers in psoriasis. Medications that inhibit IL-17 — such as the biologics Cosentyx (secukinumab) and Taltz (ixekizumab) — have been authorized by the United States Food and Drug Administration (FDA) to treat moderate to severe psoriasis.

A protein similar to IL-17, called IL-6, has long been associated with psoriasis. One study looking at IL-6 and the Koebner phenomenon showed an increase of IL-6 in skin cells from people who had a Koebner response compared to those who had no response. Actemra (tocilizumab) is an IL-6 inhibitor approved by the FDA for the treatment of rheumatoid arthritis, and it has also been reported to improve symptoms of palmoplantar pustular psoriasis and psoriatic arthritis.

Another important molecule thought to be responsible for the Koebner phenomenon is CCL20, which is a signaling protein. It recruits a special type of immune cell called a T cell. One study shows that damaged skin cells make more CCL20. Researchers have recently discovered the molecules that help turn on CCL20 in skin cells.

These are just a few of the studies that have been done to determine how molecules of the autoimmune response cause the Koebner phenomenon. Studies like these are exciting because they provide the basis for expanding treatments.

Treatments for Skin Injuries With Psoriasis Flare-Ups

Koebner lesions from scratches and other skin injuries are treated the same as regular psoriasis plaques. Treatments include:

  • Oral medications
  • Topical corticosteroids
  • Over-the-counter moisturizers
  • Ultraviolet light therapy that slows the growth of psoriasis

Because Koebnerized skin can crack, bleed, and lead to infection, it’s important to treat the area as soon as possible. Read more about treatments for psoriasis.

Here are some tips for preventing or managing skin injuries and lesions:

  • Avoid bruising or cutting your skin.
  • Clean and cover any wounds or scratches to prevent infection.
  • Protect your skin from the sun by wearing sunscreen.
  • Prevent dry skin with lotions and moisturizing creams, and use a humidifier in dry, cold weather.
  • Don’t touch, pick, or scratch lesions.
  • Follow your prescribed psoriasis treatment.

Consult your doctor for medical advice before starting any new treatment.

Talk With Others Who Understand

MyPsoriasisTeam is the social network for people with psoriasis and psoriatic arthritis and their loved ones. On MyPsoriasisTeam, more than 89,000 members come together to ask questions, give advice, and share their stories with others who understand life with psoriasis and psoriatic arthritis.

Are your psoriasis flares sensitive to scratches on your skin? Share your experience in the comments below, or start a conversation by posting on MyPsoriasisTeam.

References
  1. Koebner Phenomenon — StatPearls Publishing
  2. Koebner's Phenomenon in Burns: Another Complication Following Thermal Injury — Burns
  3. Tattooing and Psoriasis: A Case Series and Review of the Literature — International Journal of Dermatology
  4. Koebner Phenomenon Induced by Face Mask Ear Loops — Maedica — Journal of Clinical Medicine
  5. Mask‐Induced Psoriasis Lesions as Köebner Phenomenon During COVID‐19 Pandemic — Dermatologic Therapy
  6. Koebner Phenomenon Induced by the Use of a Computer Mouse in an Occupational Setting: Case Report — Revista Brasileira de Medicina do Trabalho
  7. Interleukin-23 and Interleukin-17: Importance in Pathogenesis and Therapy of Psoriasis — Dermatology Online Journal
  8. Experimentally Induced Psoriatic Lesion Associates With Interleukin (IL)-6 in Mast Cells and Appearance of Dermal Cells Expressing IL-33 and IL-6 Receptor — Clinical & Experimental Immunology
  9. Successful Effect of Tocilizumab in Anti-TNF-α-Induced Palmoplantar Pustulosis in Rheumatoid Arthritis — Joint Bone Spine
  10. Successful Use of Tocilizumab in a Patient With Psoriatic Arthritis — Rheumatology
  11. Cyto/Chemokine Profile of In Vitro Scratched Keratinocyte Model: Implications of Significant Upregulation of CCL20, CXCL8 and IL36G in Koebner Phenomenon — Journal of Dermatological Science
  12. The EGFR-ERK/JNK-CCL20 Pathway in Scratched Keratinocytes May Underpin Koebnerization in Psoriasis Patients — International Journal of Molecular Sciences
  13. Medical Definition of Interleukin-1 — MedicineNet
All updates must be accompanied by text or a picture.
Ariel D. Teitel, M.D., M.B.A. is the clinical associate professor of medicine at the NYU Langone Medical Center in New York. Review provided by VeriMed Healthcare Network. Learn more about him here.
Erik Linklater, Ph.D. has a Ph.D. in molecular biology from the University of Colorado, where he is currently a postdoctoral researcher. Learn more about him here.

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