Keloid Formation: Causes, Early Signs and Prevention

How keloids form

Normal scar formation runs in overlapping phases: inflammation, then a building phase when fibroblast cells lay down collagen, then remodeling, when the scar flattens and fades over about a year.

In keloid formation, the building phase does not switch off. Fibroblasts in the wound stay overactive and keep producing large amounts of thick, disorganized collagen. They respond excessively to growth factors such as TGF-beta, and the scar keeps expanding into the surrounding normal skin, much like a benign tumor. Ongoing low-grade inflammation and skin tension both drive the process.

A key point: a keloid grows beyond the borders of the original wound and does not shrink on its own. That distinguishes it from a hypertrophic scar, which is raised but stays within the wound and usually flattens over time.

Why keloids form in some people and not others

Genetics and skin type

Keloids are much more common in people of African, Asian and Hispanic descent, and in people with a family history. Many people with keloids have a relative with them. Some rare genetic syndromes also predispose to keloids.

Age and hormones

Most keloids form between about 10 and 30 years old. Puberty and pregnancy can trigger new keloids or make existing ones grow, which suggests hormones play a role. Keloids are uncommon in young children and older adults.

Location and skin tension

High-tension, high-movement areas form keloids most readily: the breastbone, shoulders, upper back and upper arms. The earlobe is the classic site after piercing. The palms, soles and eyelids are rarely affected.

The type of injury

Almost any break in the skin can start a keloid, including:

• ear and body piercings
• surgical incisions, especially on the chest, and cesarean scars
• acne, particularly on the jaw, chest and back
• burns
• vaccination sites, especially on the upper arm
• tattoos
• insect bites, chickenpox spots and scratches
• ingrown hairs and razor bumps

Wounds that become infected, heal slowly or are closed under tension carry a higher risk. Some keloids appear with no injury the person remembers, called "spontaneous" keloids, usually on the chest.

Early signs that a keloid is forming

• a scar that is still getting thicker, firmer or redder 1 to 3 months after the wound closed
• itching, tenderness or a burning or prickling feeling in the scar
• the raised edge starting to creep past the original wound line
• a smooth, shiny, rubbery bump at a piercing site, often on the back of the earlobe

Treating at this stage is easier and more effective than treating a mature keloid. A dermatologist can confirm the diagnosis by examination. A biopsy is only needed if the growth looks unusual.

How to prevent keloids

If you have had a keloid before, or have a strong family history:

• Avoid elective skin trauma where possible: new piercings, tattoos and cosmetic procedures, especially on the chest, shoulders and ears.
• Tell your surgeon before any operation. They can plan incisions along skin lines, minimize tension and use preventive treatment.
• Treat acne early and avoid squeezing spots.
• Use silicone gel or sheets on new wounds once the skin has closed, typically for at least 2 to 3 months, worn 12 or more hours a day.
• Apply pressure for earlobe wounds with pressure earrings, worn for many hours a day for several months after a piercing or keloid removal.
• Protect healing scars from the sun, which can darken them.
• Get early steroid injections into a scar that starts to thicken. Some surgeons inject at the time of surgery for high-risk patients.
• Look after wounds to avoid infection and keep them moist and covered while healing.

Treating a keloid once it has formed

No single treatment works for everyone, and keloids frequently come back. Treatment is usually a combination:

• Corticosteroid injections (triamcinolone) every 4 to 6 weeks flatten and soften most keloids and ease itching. Side effects include thinning or lightening of the surrounding skin.
• Silicone sheets and pressure reduce thickness over months.
• Cryotherapy (freezing) works best on small keloids but can lighten darker skin.
• Surgery removes the keloid but has a high recurrence rate if used alone, so it is combined with steroid injections, pressure or radiation.
• Radiation therapy after surgery lowers recurrence, mainly for stubborn keloids.
• Other options: 5-fluorouracil injections, pulsed-dye laser for redness, and newer approaches such as botulinum toxin, studied with mixed results.

For a fuller look at treatment and outcomes, see our page on keloids.

Complications

Keloids are not cancerous and do not turn into cancer. They can still cause problems: persistent itch and pain, restricted movement when over a joint, catching on clothing, and distress about appearance. Large keloids can occasionally become infected.

Frequently asked questions

Why do keloids form?

Keloids form when fibroblast cells keep making collagen long after a wound has healed. Genetic tendency, darker skin, ages 10 to 30, hormones and high-tension skin areas such as the chest and earlobes all make this overactive healing more likely.

How long after a piercing does a keloid form?

A keloid usually begins 1 to 3 months after a piercing, as a firm bump that keeps growing, often on the back of the earlobe. Occasionally it appears up to a year later. A bump that keeps enlarging after the piercing has healed should be shown to a dermatologist.

How can I tell if my scar is turning into a keloid?

Signs include a scar that keeps thickening months after healing, grows past the original wound edges, and feels itchy, tender or rubbery. A hypertrophic scar stays within the wound and usually flattens. A dermatologist can tell the difference by examining it.

Can keloids be prevented if they run in my family?

Often they can be reduced. Avoid elective piercings and tattoos in high-risk areas, tell surgeons about your history, use silicone and pressure on healing wounds, and get early steroid injections into any scar that starts to thicken.

Are keloids dangerous?

No. Keloids are benign and do not become cancer. However, they can be itchy, painful and distressing, and they tend to return after removal. Any rapidly growing or bleeding lump that does not follow an injury should be checked, as other growths can look similar.