Keloid scars: what they are, why they come back and how they are treated

What is a keloid scar?

A keloid is a type of raised, thick scar that grows beyond the borders of the original wound into the surrounding healthy skin. It is one of the two types of "active" scars, alongside the hypertrophic scar, which are covered in depth in the complete guide to scars. A keloid can be firm and tender, and sometimes painful or itchy, and its color tends to differ from the surrounding skin: pink, reddish-purple or brown, depending on skin tone¹.

Keloid scars differ from an ordinary raised scar in that they extend beyond the borders of the original wound and do not regress on their own, so they require planned treatment and follow-up.

Contrary to intuition, a keloid does not have to follow a major injury. It can form after a pimple, an insect bite, an injection, a piercing or a small burn, and sometimes with no identifiable cause at all²⁷.

How do you tell a keloid from a hypertrophic scar?

The key difference is the borders: a hypertrophic scar stays within the wound line, and a keloid goes beyond it. A hypertrophic scar usually appears within weeks of the injury, grows for about 3 to 6 months and then tends to regress gradually. A keloid, by contrast, can appear months or even years after the injury, and usually does not regress on its own¹²⁸.

One tool used for clinical distinction is the JSW Scar Scale: a score of 5 or below is classified as a normal mature scar, a score of 6 to 15 corresponds to a hypertrophic scar, and a score of 16 or above corresponds to a keloid⁵. Distinguishing between the types matters a great deal, because keloids have much higher recurrence rates, so the treatment approach is different.

Why do keloids form, and who is at higher risk?

A keloid forms when the natural healing process "does not stop in time", and local, systemic and genetic risk factors affect the likelihood of this happening. Among the local factors, the main one is mechanical tension on the wound, which is why keloids are common in areas that stretch, such as the chest and shoulders. Systemic factors, such as high blood pressure, as well as genetics and lifestyle, also contribute³.

The most prominent risk factors:

• Skin tone: keloids are considerably more common in brown or Black skin, and in people of African, Asian and Hispanic descent²⁷.
• Age: the risk is highest between the ages of 10 and 30².
• A personal or family history of keloids².
• Pregnancy: keloids may worsen during pregnancy and improve after delivery. One explanation is the effect of estrogen as a systemic factor³.

In Israel, with its population diverse in skin tone, this is an important consideration in assessing risk and choosing treatment.

Where do keloids usually appear?

Keloids are especially common on the ears, shoulders, upper back and chest, areas where the skin is under high mechanical tension²¹. An ear keloid after piercing is a particularly common subtype, which is why people with a tendency to keloids are usually advised to avoid further piercings, or to seek advice beforehand.

What treatments are there for keloids, and how successful are they?

No single treatment ensures success, so the approach accepted in international guidelines is to combine treatments according to the keloid's size, location and response to previous treatment³⁹. The table summarizes the main options:

Intralesional steroid injection is one of only two treatments that were already considered sufficiently established in the first international recommendations of 2002¹⁴. More details on injections, including side effects, are in the guide to scar injections. How many injections are needed, how often and what the side effects are is explained on the page steroid injections for keloids, and the combination with 5-FU on the page 5-FU combined with Kenalog for keloids. On freezing with liquid nitrogen, alone or before an injection, see keloid cryotherapy with liquid nitrogen.

Do silicone sheets and pressure help keloids?

Silicone and pressure are home treatments that help mainly to prevent a keloid or its recurrence, and less to shrink an established keloid. Silicone sheets or gel can help flatten a keloid, and they are also used on a new keloid, after an injury and after surgery to remove a keloid¹⁵. A Cochrane review of 20 trials found an improvement in the thickness and color of raised scars, but the evidence is weak and the quality of the studies is low¹⁶. According to the American Academy of Dermatology, once the wound has closed, the gel is applied or a sheet is put on every day for about six months¹⁷. Details on use are on the page silicone for scars.

Continuous pressure reduces blood flow to the scar and is used mainly on the ear, with a pressure earring, after a keloid has been excised. To work, it needs to be worn 12 to 20 hours a day for several months¹⁵.

A bump on the ear after piercing: according to the American Academy of Dermatology, when the skin of the earlobe starts to thicken, a keloid can sometimes be prevented by acting quickly: removing the earring and switching to a pressure earring, worn for at least 12 hours a day and preferably 20, for 4 to 6 months¹⁷. It is worth showing the bump to a doctor, because an infection or an ordinary scar can look similar at an early stage.

Why is excision alone never enough?

Because excising a keloid without adjuvant treatment ends with the keloid coming back in 45 to 100 percent of cases, sometimes even larger than the original³. This is probably the most common mistake in keloid treatment: a "clean" surgical removal creates a new wound, and if no treatment is added to prevent the process from recurring (radiation therapy, steroid injection, 5-FU or a combination), the new wound may turn into a keloid again.

That is why the accepted recommendation is always to combine surgery with an adjuvant treatment, and not to offer excision as a stand-alone solution⁶. What such a plan looks like in practice, from excision techniques to the follow-up schedule, is explained on the page surgical keloid removal.

Is radiation therapy for keloids safe?

Radiation therapy after keloid excision substantially reduces the chance of recurrence, and it is intended mainly for keloids that are resistant to other treatments. A meta-analysis that included 72 studies and about 9,000 keloids found a recurrence rate of about 22 percent with surgery combined with radiation, compared with 37 percent with radiation alone; with brachytherapy the recurrence rate was lower, about 15 percent. The highest risk of recurrence was in chest keloids, and the most common side effect was a change in pigmentation¹². A more recent meta-analysis, which included over a hundred studies and about 10,700 lesions, found recurrence rates of 14 to 18 percent depending on the method, with no significant difference between earlier and later radiation after surgery¹³. On the ear, where keloids are especially common, recurrence rates after steroid injection and after radiation were similar in the short term, but the effect of the steroid weakened over time¹⁸.

As for safety: there are isolated case reports of a risk of a secondary tumor following radiation, collected over about 70 years, but the causal link is unclear, and accepted protocols keep to a maximum effective and safe dose³. Both the American Academy of Dermatology and the British Association of Dermatologists mention this risk in their explanations for treatment consent¹⁵¹⁹. The decision on radiation therapy is made together with a radiation oncologist, and it is usually reserved for resistant cases or for large, recurrent keloids.

Will the keloid come back after treatment?

This is the main risk in keloid treatment, so it is important to talk about it honestly in advance. Even after steroid injections, the most common treatment, about a third of keloids come back within a year, and up to half come back within five years, according to one review⁴. Patient organizations also report similar recurrence rates, ranging from about 50 to 80 percent depending on the treatment and the length of follow-up¹⁵¹⁹.

Because of this, the recommendation is not to stop follow-up after a "successful" treatment. Guidelines recommend follow-up for at least 18 to 24 months after keloid treatment, in order to detect signs of recurrence early and add treatment as needed³.

How can a new keloid be prevented?

People with a tendency to keloids (a personal or family history) can reduce their risk in a few simple ways²¹⁹⁸:

• Avoid piercings, tattoos and unnecessary surgery, and think twice about any elective procedure.
• Tell the surgeon about the tendency before any planned surgery, so that preventive treatment can be considered.
• Pressure earrings after ear piercing can help prevent a keloid at the piercing site².
• When it comes to prevention after surgery, a steroid injection about 10 to 14 days after the operation is considered preferable to an injection before or during the operation⁸.

When is a biopsy needed?

When the "keloid" grows unusually fast, bleeds, hurts with varying intensity, or looks atypical, a biopsy is advisable to rule out another diagnosis. A keloid itself is not a cancerous tumor and is not contagious⁷, but some rare skin tumors, including dermatofibrosarcoma protuberans, squamous cell carcinoma and even amelanotic melanoma, can look similar to a keloid at first glance⁵. The American Academy of Dermatology also stresses that certain skin cancers can look like an ordinary scar⁶. A lesion that behaves "not like a typical keloid" therefore requires an examination and sometimes a biopsy, and not only empirical treatment. An "ordinary" keloid that bothers you is also worth having examined: the earlier you start, the more treatment options there are to choose from.

What does a keloid consultation with Dr. Dana Buchbut look like?

The consultation begins with an examination that distinguishes a keloid from a hypertrophic scar, and with a personal plan built on the assumption that the keloid may come back, and that therefore includes follow-up. The plan may include scar injection, instructions for silicone and pressure, and prevention advice for those with a tendency to keloids. Treatments such as radiation therapy after excision are done in cooperation with other providers, as described above. In line with the guidelines, follow-up for at least 18 to 24 months after treatment is recommended. A lesion that grows quickly or looks unusual is referred for further medical evaluation.

Terms on this page: hypertrophic scar · 5-FU · liquid nitrogen cryotherapy · triamcinolone · botulinum toxin · full glossary

The information on this page is general and for education only. It does not replace an examination, diagnosis or personal medical advice. A decision about treatment is made only after an examination.