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What is a hypertrophic scar?
A hypertrophic scar is a thick raised scar. It’s an abnormal response to wound healing in which extra connective tissue forms within the original wound area. The result a raised scar.
Normally, a small wound to the top layer of your skin heals nicely. New skin forms as the wound heals. With deeper wounds (into the dermis layer and lower), your body responds by making collagen to repair the wound. Collagen is thicker than the rest of your skin. This thicker, less flexible tissue becomes a scar. Most scars are flat. However, sometimes your body makes extra collagen that results in a raised scar. This type of raised scar can be either a hypertrophic scar or a keloid.
What’s the difference between a hypertrophic scar and a keloid scar?
The key visible difference between hypertrophic and keloid scars is the degree of the spread of the scar around the original wound. With hypertrophic scars, the extra connective tissue that forms within the original wound stays within that area. With keloid scars, the extra connective tissue that forms extends beyond the original wound area. This and other differences between these two raised scars are shown in the table.
|Hypertrophic Scars Versus Keloids|
|Appearance around wound||Stays within wound area||Extends beyond wound area. Can grow very large.|
|Color||Pink to red||Red to purple|
|Where found on body||More common in taut skin areas||Taut and less taut skin areas|
Collagen arrangement (microscopically)
|Collagen fibers are parallel to upper skin layer (epidermis)||Collagen fibers have random, disorganized arrangement. More blood vessels are present.|
Time to develop
|Develops 1 to 2 months after injury||Develops months to years after injury|
Scar changing to cancer
|Less frequently seen||Increased risk|
Ease of treatment, success
|Easier to treat||Harder to treat, high return rate|
|Goes away on its own||May become less noticeable with time||Never goes away without treatment|
Where do hypertrophic scars commonly occur?
Hypertrophic scars are more common in areas of the body where your skin is taut, such as your back, chest, shoulders and upper arms, elbows and other joints. However, hypertrophic scars can occur anywhere on your skin where you’ve had a skin injury or wound.
Scar tissue can form from skin injury or wounds resulting from accidental trauma, inflammation, burns and surgical incisions. There are many other types of skin scars, each with their own appearance, causes and treatments.
Are there risk factors that increase the chance of developing a hypertrophic scar?
Factors that increase the risk of hypertrophic scarring include:
- Burn wounds, especially second- and third-degree burns.
- Systemic (whole body) inflammation.
- Poor wound healing due to infection.
- Genetics. Raised scarring, especially keloids, run in certain families.
Are hypertrophic scars dangerous?
No, they’re not dangerous or life-threatening. They’re mainly a cosmetic (physical appearance) issue. However, hypertrophic scars can cause pain or itching. Also, if they form over a joint, they can limit your movement so you may want to have them treated.
Symptoms and Causes
What causes hypertrophic scars?
Wounds go through three phases of healing – inflammation, proliferation and remodeling. Scar tissue forms during the remodeling phase. Specific types of cells such as fibroblasts and myofibroblasts and certain signaling molecules such as transforming growth factor-beta and tumor necrosis factor are all involved in wound healing and the creation of new tissue. In both hypertrophic scars and keloid scars, this repair response goes haywire. Although the reason is not fully understood, the result is the abnormal production of extra collagen and a decrease in elastin, which lead to these undesirable thick, raised stiff scars.
What are the signs and symptoms of a hypertrophic scar?
The signs and symptoms of a hypertrophic scar are easy to recognize. They include:
- Hard or thickened raised tissue over your wound site.
- Pink to red to purple skin color over your wound site.
- Scar appears most commonly on the upper trunk of your body – your back, chest, shoulders, upper arms – and skin that covers your joints.
- Scar develops one to two months after injury.
- Scar may cause irritation, itching, tenderness and/or pain.
- Scar on your skin over a joint may limit your joint’s normal movement.
Diagnosis and Tests
How are hypertrophic scars diagnosed?
Your healthcare provider will be able to make the diagnosis of hypertrophic scarring by examining the site of the scar. A biopsy may be ordered if the scar continues to worsen or change.
Management and Treatment
How are hypertrophic scars treated?
The goals of hypertrophic scar treatment are to flatten, soften, reduce the size, lighten the color and ease any existing pain and itch of your scar. Your healthcare provider -- usually a dermatologist or plastic surgeon – may wait a few months or even up to year before treating your scar. This allows the scar enough time to fully heal and possibly reduce in size and flatten on its own.
The most common treatment options for hypertrophic scars include:
- Corticosteroid injections: This is a main treatment for hypertrophic scars. Injections are made into the scar tissue. They flatten and soften scar tissue and ease pain and itch. Several shots may be needed, each given a few weeks apart.
- Laser therapy: Long pulsed Nd:YAG lasers or pulsed dye lasers are the lasers commonly used to treat hypertrophic scars and keloids. Lasers often target blood vessels in the scar which can remove these blood vessels and prevent scar growth. They also can lighten the red or pink color often seen in scars and reduce pain, itch and hardness. A fractionated laser may be used to put microscopic holes in the scar to soften it and tell it to remodel. This is particularly good for scars that may limit range of motion over joints or have not completely responded to other methods.
- Bleomycin or 5-FU (fluorouracil) injection: Either of these medication choices are injected directly into the scar tissue. The medication flattens the scar and reduces itch and pain by damaging the cells that have overgrown. These injections are usually combined with laser therapy or corticosteroid injection to reduce the side effects of the medication.
- Cryotherapy: Cryotherapy uses extreme cold (liquid nitrogen) to freeze and slowly destroy scar tissue, which helps flatten the raised tissue. This treatment may be combined with the other injection treatment options to further reduce the scar.
- Surgery: Sometimes surgery is performed to cut out the scar or redirect the lines of tension on the scar. Usually, surgery is considered when other treatment options have failed. This is because the surgery itself can result in scarring. Surgery may be combined with other treatment to improve the results.
There are several other treatments that can be tried to reduce hypertrophic scars. Many of these don’t have a lot of strong evidence of a high degree of success. After reviewing your scar, your healthcare provider will determine which treatments or combination of treatments have the greatest chance for the best outcome for your particular scar. This decision is made based on your age, prior wound healing experience, size and location of the scar and other factors.
Some common self-help treatments include:
- Silicone gel: Silicone sheets or ointment are used after the wound closes to prevent or reduce a raised scar. The self-adhesive sheets need to be worn every day, all day, usually for several months or longer. This product reportedly manages all aspects of the scar: reducing the size, redness, hardness and itchiness. Follow the instructions on the product packaging. Call your provider if any side effects occur.
- Moist dressing with pressure garment: Apply petroleum jelly or a similar ointment to a non-adhesive flexible pad. Place over wound and affix to your skin with paper tape. Some studies have shown that applying pressure over the dressing, such as with an elastic wrap, spandex bandage or ACE bandage, reduces raised scars and improves outcomes.
Ask your provider about these and any other self-home treatments. They can tell you which product will work best for your particular scar.
Are hypertrophic scars caused by burns treated the same way as other skin injuries?
Hypertrophic scars that result from burn wounds are more difficult to treat. Superficial burn wounds usually heal without forming hypertrophic scars. Deep burn wounds are harder to treat. Many dermatologic and plastic surgeons treat these by removing the burned area and then using a skin graft.
Laser therapy is also often used to treat hypertrophic scars caused by burns. Laser therapy can improve the color of the scar, the height of the scar, reduce skin tension on the scar, and improve pain and itchiness. You should also follow your provider’s recommendations about proper nutrition and vitamins to improve hypertrophic scar healing.
What are the complications of treating hypertrophic scars?
All treatments have possible side effects. Some may possibly worsen the scar. Scars may return, darken or overly lighten in color. Be sure to ask your healthcare provider about the possible side effects of all treatment options being considered for your scar.
Can hypertrophic scars be prevented?
If you know that you are prone to forming hypertrophic scars, you might want to avoid elective surgeries. Be sure to bring this up with your doctor during any consultation. Correction of any vitamin deficiencies such as Vitamin D prior to any elective surgery may also be helpful.
Outlook / Prognosis
What should I expect if I have a hypertrophic scar?
Hypertrophic scars are mainly a cosmetic issue and are not dangerous or life-threatening. However, you might want to get them checked by a dermatologist or plastic surgeon, as they could hide a skin cancer (they are not cancerous themselves).
Do all hypertrophic scars need to be treated?
No, not necessarily. If the scar is not in a location that you find disturbing to your appearance, doesn't cause bothersome pain or itching or isn’t restricting your movement, you don’t need to have it treated. If your scar disturbs you, see a dermatologist or plastic surgeon.
Are hypertrophic scars cancerous?
Hypertrophic scars are not cancerous themselves. However, if you have one or more, it’s wise to get them checked. Sometimes these scars can hide skin cancer. Your provider can conduct a careful evaluation of these scars and all of your skin growths and markings.
When you are outside, be sure to cover your scars with clothing or apply a broad-spectrum sunscreen product to your skin with SPF of at least 30. Avoid tanning beds. They can increase your risk of developing skin cancer.
How should I properly care for wound injuries at home to prevent or lessen scarring?
If you have a wound injury or an incision wound following surgery, always follow the wound care instructions given to you by your doctor. These instructions will tell you how to clean and care for your wound to promote healing and prevent scarring. Let your provider know if you are prone to scarring so they can more closely follow you in case you need treatment for a hypertrophic scar. Keep your follow-up appointments so your provider can check on how well your wound is healing.
Some general, self-care tips for proper wound healing include:
- Keep your wound clean.
- Wash your wound with soap and water. Never use hydrogen peroxide. This chemical can further damage your skin.
- Keep your wound moist as it heals. Apply petroleum jelly or a similar ointment. If wounds are large, sometimes a special dressing, such as Duoderm®, may be used to cover the wound. Follow the instructions for use of this product.
- Change your bandage daily or more frequently as directed by your doctor. Use non-adhesive bandages and paper tape for affixing to your skin.
- Always contact your provider if you have any questions on wound care or healing.
- After your wound has healed, always apply broad-spectrum (UVA and UVB) sunscreen with SPF of at least 30 to your skin.
A note from Cleveland Clinic
Hypertrophic scars are mainly a cosmetic issue. You may or may not choose to get them treated. Two reasons to perhaps see a dermatologist are that the scars could possibly hide a skin cancer or the location of the scar limits your movement (for instance if it forms over a joint). If you choose to treat, there are many options.
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