Hypertrophic Scar

In short: A hypertrophic scar is a raised scar caused by excess collagen build-up during wound healing. It may be red, itchy or tender, but it does not spread beyond the original wound border and may partly regress over time. A keloid, by contrast, extends beyond the border and has a high tendency to recur. Prevention relies on wound care, reducing tension and silicone; treatment mainly uses silicone, corticosteroid injection into the scar and laser.

What is a hypertrophic scar?

Normal wound healing moves from an inflammatory phase to new tissue formation and then a remodelling (maturation) phase that lasts for months. When this balance is disturbed, inflammation is prolonged, fibroblasts become overactive and excess collagen builds up in the dermis. The resulting raised, firm, often red or pink scar is called a "hypertrophic scar".

A hypertrophic scar usually becomes noticeable within weeks of the injury, may thicken over several months and then tends to flatten and fade partly over months to years. Itching, tenderness and a feeling of tightness are common. When it forms over a joint it can become a contracture that restricts movement.

How it differs from a keloid

Hypertrophic scars and keloids both belong to the group of "pathological scars" and can look alike at first glance. However, their natural course and response to treatment differ:

• Border: A hypertrophic scar stays within the original wound border; a keloid spreads beyond it into surrounding healthy skin.
• Course: A hypertrophic scar may partly regress over time; a keloid usually does not regress on its own and may keep growing for years.
• Onset: A hypertrophic scar usually appears soon after the injury; a keloid can develop months later, even after a very minor injury.
• Location: Hypertrophic scars are common in areas under tension, in burns and around joints; keloids are common on the earlobes, front of the chest, shoulders and upper back.
• Recurrence: Keloids recur at high rates when removed by surgery alone, so surgery on its own is generally not recommended.

The Japan Scar Workshop (JSW) consensus document stresses that keloids and hypertrophic scars are more common and more severe in people of Asian and African descent, and highlights the importance of distinguishing these scars from benign and malignant tumours that can look similar. Making this distinction, and planning a biopsy when needed, is the physician's responsibility.

How does it form and what are the risk factors?

Prolonged inflammation and overactive fibroblasts lie at the heart of hypertrophic scarring. Consensus documents particularly emphasise mechanical tension: a wound that is constantly stretched or moved produces more inflammation and collagen as it heals.

• Areas under tension (front of the chest, shoulders, over joints) and wounds running across the skin's natural lines
• Burns, especially deep and slow-healing burns
• Wound infection, wound breakdown and delayed healing
• Personal and family predisposition, younger age and darker skin types
• Acne (especially inflamed acne on the trunk and jawline), ear piercing, tattoos, body piercings and similar minor injuries (mainly for keloids)

How is it assessed?

Assessment starts with a history covering when and how the scar formed, whether it is still growing and whether it itches or hurts. Examination looks at the scar's borders, thickness, colour, firmness and effect on joint movement, and standard photographs are taken. Tools such as the Vancouver Scar Scale, the Patient and Observer Scar Assessment Scale (POSAS) or the JSW Scar Scale can be used for monitoring and comparison. The JSW scale also scores patient and site risk factors to help distinguish keloids, hypertrophic scars and mature scars.

Fitzpatrick skin type, all medicines and supplements, previous treatments and any history of keloids are recorded. A lesion that grows quickly, bleeds, ulcerates or looks atypical may need a biopsy to confirm the diagnosis.

Prevention

For wounds at high risk of hypertrophic scarring, prevention is more effective than treatment after the scar has formed. Current international recommendations highlight the following steps:

• Good wound care: Preventing infection and helping the wound close as quickly as possible.
• Reducing tension: Appropriate closure technique for surgical wounds, followed by support such as taping.
• Silicone: Once the wound has fully closed, silicone gel or sheeting is recommended as prevention for people at risk. A Cochrane review notes that the studies showing silicone reduces hypertrophic scarring in high-risk people are highly susceptible to bias and that the evidence is weak.
• Sun protection: Protecting an immature scar from the sun helps reduce the risk of lasting colour change.

Treatment options and level of evidence

The 2014 updated international recommendations state that combining several methods offers the greatest chance of success in treating hypertrophic scars and keloids. The levels of evidence below are summarised from the sources on this page.

• Silicone gel or sheeting: International practical guidelines regard it as first-line for preventing and treating hypertrophic scars and keloids; it is non-invasive and has few side effects. In the Cochrane review, treatment studies showed improvements in scar thickness and colour, but these studies were of low quality. It requires regular, long-term use. Evidence: low to moderate; widely recommended.
• Pressure therapy: Used mainly for extensive burn scars. A 2024 Cochrane review found the evidence on pressure garments for preventing hypertrophic scarring after burns very uncertain and insufficient to support a recommendation. Its role in facial aesthetics is limited. Evidence: very low.
• Intralesional corticosteroid: An injection of corticosteroid (most often triamcinolone acetonide) into the scar tissue; by suppressing inflammation and collagen production it softens and flattens the scar. It is a first-line treatment for keloids and is also often used for prominent, thick hypertrophic scars. An international expert consensus (KECORT) reached agreement on many aspects of technique but not on dosing. The drug, strength, amount and interval between sessions are decided entirely by the physician. Evidence: moderate.
• Corticosteroid combined with 5-fluorouracil (5-FU): In a meta-analysis of 13 studies (12 randomised), the combination showed higher efficacy than corticosteroid alone or 5-FU alone, and visible small blood vessels were less frequent than with corticosteroid alone. The authors stress that patient-reported outcomes should be included in future studies. 5-FU is a cancer medicine; its use for scars is outside its approved indications and is given only on a physician's decision. Evidence: moderate.
• Laser: Vascular lasers (for example the pulsed dye laser) target redness and itching, and fractional ablative lasers target thickness, texture and restricted movement; fractional laser can also be used to help deliver medicine into the scar. The 2020 international consensus lists lasers among the first-line treatments for traumatic scars. Much of the evidence rests on consensus and small studies. Evidence: moderate.
• Other options: Methods such as cryotherapy, surgical revision and, for keloids, radiotherapy after surgery are used in selected patients at specialist centres.

Risks and precautions in darker skin

Possible side effects of corticosteroid injection include skin thinning (atrophy) around the scar, lightening of skin colour (hypopigmentation), visible small blood vessels and pain during injection; lightening can be more noticeable in darker skin. Temporary redness, bruising and crusting are common after laser; the risk of post-inflammatory hyperpigmentation is higher in darker skin. In people prone to keloids every new procedure may carry a risk of a new scar, so the choice of method needs particular care.

Tell your physician about all medicines and supplements you take, including blood thinners. Never stop a prescribed medicine without asking the doctor who prescribed it.

Realistic expectations

The aim of treatment is to flatten and soften the scar and reduce redness and itching; the scar does not disappear completely. Most cases need several sessions and a combination of methods. Methods such as silicone require months of regular use. Because hypertrophic scars can also regress on their own, time matters when judging results. Keloids can recur after treatment and need long-term follow-up.

When to refer to dermatology or plastic surgery

• When a keloid is suspected, especially large, multiple or fast-growing keloids
• When the lesion bleeds, ulcerates, is painful or does not look like a typical scar (for biopsy and diagnosis)
• When there is a contracture over a joint or loss of function
• For extensive burn scars
• When the scar progresses despite first-line treatment, or when advanced treatment such as surgery or radiotherapy may be needed
• In children and during pregnancy

How this clinic approaches hypertrophic scars

At our clinic, assessment of a raised scar begins with a consultation with medical aesthetics physician Dr. Hamza Gemici. The first question is whether the scar is a hypertrophic scar, a keloid or another kind of lesion; the scar is photographed and symptoms and risk factors are recorded. Where appropriate, options such as silicone, intralesional treatment and laser are discussed together with their levels of evidence and risks, and the plan is agreed jointly. Where a keloid is suspected, the appearance is atypical or surgery may be needed, we work with dermatology or plastic surgery colleagues.

Sources

This content is based on the 2014 updated international scar management recommendations (two parts) and practical guidelines, the Japan Scar Workshop 2018 consensus document, Cochrane reviews of silicone and pressure therapy, the 2020 international consensus on laser treatment of traumatic scars, a meta-analysis of corticosteroid combined with 5-FU and the KECORT consensus on intralesional corticosteroid in keloids. Full citations are given in the reference list.