Hypertrophic scars and keloids both form due to excess collagen during wound healing. But hypertrophic scars stay within the confines of the wound, while keloids can grow beyond. Keloids are also much more difficult to treat.

Hypertrophic scars and keloids are types of scars resulting from an injury to the skin. They are more obvious than typical scars that are flat and relatively invisible. They are both the result of too much scar tissue developing near the site of a skin injury.

Hypertrophic scars grow right after your wound has healed and stay within the injury site. Keloids take longer to appear and can spread beyond the injury.

Hypertrophic scars should resolve over time with or without treatment. Keloids may remain on your body long term despite efforts to reduce them.

Keep reading to learn more about what keloids and hypertrophic scars have in common and how they differ.

Hypertrophic scars are thickened scars that appear after you experience a skin injury. They may be raised or flat, and stay within the boundaries of the wound.

Hypertrophic scars occur when your body makes too much collagen while trying to repair the wound. This could be due to infection or increased tension on the wound. Collagen is thicker than your skin, which is why these scars may appear raised or feel rough.

Any of the following can trigger a hypertrophic scar to form:

  • cuts
  • acne
  • insect bites
  • burns
  • skin infections

Keloids are raised scar-like skin growths. Unlike hypertrophic scars, the connective tissues in keloids continue to grow beyond the wound site. While hypertrophic scars have about three times as much collagen production as is typical, keloids have about 20 times as much.

The collagen fibers also arrange themselves differently in keloids. In hypertrophic scars, the collagen fibers have a regular pattern. But in keloids, they seem to arrange themselves randomly.

Doctors consider keloids to be benign tumors on your body. This means that they are not harmful to your overall health.

Keloids may appear after a major injury to the skin or from just a minor wound. The same things that trigger a hypertrophic scar can also trigger a keloid.

According to the American Osteopathic College of Dermatology, up to 10% of people develop keloids.

Genetics may be a risk factor, per the American Academy of Dermatology, as about one-third of people with keloids have a first-degree relative (parent, sibling, or child) who develops keloids. They occur more frequently in people who have darker skin.

Both men and women can develop them at equal rates.

At first glance, these scars may present in the same way. They may:

  • be raised above your skin
  • cause discomfort
  • be itchy

Here are some differences between the two scars:

Hypertrophic scarsKeloids
Sizestay within the area of the initial woundgrow beyond the initial wound
Onsetbegin within a month or two after the initial wound and continue to grow for many monthsbegin a few months or several years after the wound and grow over time
Outlookshrink after a yeardo not shrink in size
Colormay be a lighter pink or red colormay be a darker purple-red color
Effect on movementcan stiffen joint movement because the scar shortens tissuesdo not affect joint movement
Incidencemore commonless common
Locationcan develop anywhere on the body but often near sites where a wound is infected, irritated, or untreated or where a joint moves the skindevelop on certain areas of the body, including the upper torso, earlobes, and cheeks

Keloids and hypertrophic scars in skin of color

It’s important to note that according to research, there are some distinctive differences in how these hypertrophic scars and keloids develop and look on skin of color. Differences can include:

  • hyperpigmentation
  • scars covering wider areas
  • scar developing over a shorter time, including reports of spontaneous development
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Despite some similarities, hypertrophic scars will not turn into keloids.

Current scientific research suggests that they are different from each other. A 2020 review of studies found no evidence from research that they are the same thing. The study encouraged the medical community to continue to treat them separately until any new findings indicate that they may be similar.

Hypertrophic scars may get smaller over time without any treatment. Sometimes treatment may be necessary.

Similar treatments may help both types of scars. But incomplete treatment could cause keloids to grow over time.

You may try to reduce discomfort by:

  • applying creams, lotions, gels, or oils to the site
  • wearing silicone sheets on the site for several months

Your doctor may prescribe one or a combination of the following treatments:

However, treatments are not always effective. And all treatments carry a risk of recurrence. This is most common after surgery to remove keloids.

There are some ways you can try to prevent these raised scars from forming after you have a skin injury:

  • Use a dressing that applies pressure to the wound site while it heals.
  • Make sure your doctor uses the right technique when giving you stitches. The needle should enter your skin at a 90-degree angle and create a loop through your skin as wide at the bottom as it is at the top.
  • Ask your doctor to limit the number of stitches or other sutures to close the wound.
  • Avoid elective surgeries to reduce skin trauma.

Neither keloids nor hypertrophic scars are dangerous to your overall health. But they may be painful or irritating and cause emotional distress if they affect your outward appearance.

Hypertrophic scars will generally reduce over time, while keloids may remain.

Talk with a doctor if either condition affects your physical or mental well-being. There may be some form of treatment that could work to reduce their appearance.

Hypertrophic scars and keloids are scars that appear after a skin injury. Hypertrophic scars develop over the course of a year but generally resolve over time. Keloids may develop much later and can be very persistent and unresponsive to treatment.

A doctor may advise home treatments or a combination of medical procedures to reduce them.