Can a cut turn into vitiligo? Surprisingly, the answer is yes.
If you’ve ever physically injured part of your skin and had a white spot appear that was diagnosed as vitiligo, you may have experienced something called the Koebner response. While not everyone who physically injures their body will get vitiligo and not everyone who gets vitiligo will experience the Koebner response, this unique response can be the cause or progression of vitiligo for some.
Here’s what we know about the Koebner response and vitiligo today.
What is the Koebner response?
The Koebner, or isomorphic, response occurs when a pre-existing skin condition appears on a previously unaffected area of the body after some form of physical trauma. Koebner is seen in numerous conditions, of which psoriasis, lichen planus and vitiligo are most common. Although Koebner usually happens during “active” phases of a pre-existing skin condition – a period during which the condition is actively progressing – it can also cause the initial appearance of the condition as well.
What is physical trauma? Physical trauma causing Koebner can be defined as any injury to the body. This can include a minor insect bite, a paper cut or an accidental bump on a piece of furniture. It can also result from thermal energy such as a sunburn. Interestingly, a “reverse Koebner” reaction is also possible in vitiligo, which occurs when an existing vitiligo spot re-pigments after injury to the area.
How does Koebner cause vitiligo?
There are several theories about how Koebner causes vitiligo, but none are confirmed. First, it is important to clarify what causes vitiligo. It is thought that people with vitiligo are born with genes that predispose their immune cells to attack their own melanin producing skin cells, called melanocytes. Once melanocytes are attacked, they lose the capability to produce melanin, resulting in depigmented white spots on the skin.
It is possible that physical skin damage activates these unique immune molecules and cells that only people with vitiligo have, leading to the Koebner response. Essentially, physical skin damage triggers an already primed immune system to destroy melanocytes. However, not every person with vitiligo experiences the Koebner response, so there are likely other predisposing factors that we have yet to learn about.
How many people get vitiligo because of Koebner?
The reported rates of Koebner response in people with vitiligo range widely from 21-62%. Additionally, Koebner is more likely to cause vitiligo after someone has already lost pigment from the condition. In fact, a recent observational study of 381 vitiligo patients concluded that a vitiligo history of over five years as well as more extensive and progressive vitiligo are all independent risk factors for Koebner response to occur.
Since Koebner occurs after the skin experiences some form of physical injury, body areas that are associated with repeated friction (elbows and knees), repeated movement (beltline and top of feet) or contact with the environment (hands and fingers) are the primary sites where Koebner occurs. The time interval from skin injury to Koebner spots appearing is not well studied in vitiligo, but may follow similar patterns as seen in psoriasis, occurring approximately 1-3 weeks after the triggering injury. The resulting Koebner spots are typically of identical color to regular vitiligo spots.
If the spot occurs in a known area of trauma or looks like it may have been caused by external factors (ex. linear shape resembling a cut injury), it may be a good hint that it appeared as a result of the Koebner response. It is important to distinguish these spots from other non-vitiligo white areas appearing on skin after trauma known as “post-inflammatory hypopigmentation.” This commonly occurs in patients with darker skin and , is considered a normal reaction to skin injury and is usually not as pale white as a vitiligo spot.
What does it mean if I get Koebner Response?
The clinical significance of Koebner response in vitiligo is still up for debate. A recent study published in the British Journal of Dermatology that investigated Koebner response in 700 vitiligo patients found that Koebner response can be an indicator of more severe vitiligo cases. The authors suggest that those with Koebner response are more likely to have worse responses to topical vitiligo therapy and more vitiligo spots on the body. Additionally, those with Koebner response are more likely to have had a vitiligo flare within the last year. However, more research is needed in order for us to know if those with Koebner response should receive different treatments or diagnostic tests.
How do I treat or prevent vitiligo from Koebner Response?
Currently, vitiligo spots appearing as a result of Koebner response are treated the same as regular vitiligo spots. It is hard to avoid getting vitiligo from Koebner response since even a minor injury can produce them. Wearing looser clothes and minimizing external injury or pressure on body areas are all ways to minimize the chance of Koebner response occurring.
Have you experienced the Koebner response? Share your experience below.
Uros Rakita is a fourth-year medical student studying in Chicago, Illinois. He has an interest in autoimmune and inflammatory skin conditions. In his spare time, he enjoys watching documentaries and playing basketball.