What is Hypertrophic Scarring?
Hypertrophic scarring is a type of abnormal wound healing that results in an excess of tissue that remains within the original wound area. This is different than a keloid scar, which is another kind of abnormal wound healing, where the extra tissue grows beyond the boundaries of the original wound. Despite their differences, the terms are often mistakenly used interchangeably. This discussion will describe these two types of scars in more detail.
What Causes Hypertrophic Scarring?
Some things can increase the chance of getting hypertrophic scars and keloids. A scar is called hypertrophic when it is raised and red, and a keloid is a type of scar that continues to grow and extend outside the original area of injury.
One common thing that causes these scars is tension or stress on the wound. Locations on the body that are more likely to get these scars are the back, chest, and upper arms, or any place where the skin tends to pull tight over a bone or soft tissues. On the other hand, hypertrophic scars don’t usually happen in places with less skin tension like the upper eyelids. However, in people who are prone to keloids, they can get them with any kind of scar.
There are also certain health conditions that can increase the risk of getting these scars. One study found that high blood pressure is linked to more severe keloids. Inflammation, which is the body’s response to injury or infection, is another risk factor. This can be seen after burns and can increase the chance of getting hypertrophic scars and keloids for up to a year.
Repeated injury to the same area is also a risk factor for these scars. For example, each time someone puts on or takes off an earring, it can cause a small amount of injury to the area. The spot where ear piercings are done is a common place for keloids to form, and there might be a link with nickel or other metals commonly used in earrings. Burns, especially those that affect the deeper layers of skin (second and third-degree burns), are more likely to lead to hypertrophic scarring. One study found that burn wounds that took longer than three weeks to heal were more likely to result in hypertrophic scarring. An infection is another risk factor for these scars.
Genetics, or genes you inherit from your parents, can also play a role in these scars. For example, certain gene variations have been linked to keloid scars in people of Japanese descent.
Risk Factors and Frequency for Hypertrophic Scarring
Hypertrophic scars, which are thickened, wide, often raised scars, are more commonly found in adolescents and pregnant women. Additionally, people with darker complexions have a 15% higher chance of developing another type of scar, known as keloid scars. Those with albinism, a condition characterized by a lack of pigmentation in the skin, hair, and eyes, have the least risk of getting hypertrophic scars. It’s also important to note that about 70% of deep burn injuries, which affect all layers of the skin, can result in hypertrophic scars.
Signs and Symptoms of Hypertrophic Scarring
Hypertrophic scarring and keloids are both conditions that can occur on the skin after an injury. Hypertrophic scars appear as thickened, often discolored areas over the site of a wound, particularly in areas where the skin was under a lot of tension. Keloid scars are similar but are distinctly larger, even spreading beyond the boundary of the original wound.
How quickly these scars form varies. Hypertrophic scars usually develop 1 to 2 months after an injury, whereas keloids can take months or even years to form after the initial injury. These conditions can cause itchiness, irritation, and even a type of pain known as neuropathic pain. In severe cases or when they cover a large area, these scars can also cause skin contractures, which can be disabling.
Therefore, the main distinguishing features between hypertrophic scars and keloids are:
- Hypertrophic scars: thickened and sometimes discolored areas over a wound, developing 1 to 2 months after an injury
- Keloid scars: significantly larger than the original wound and extend beyond its boundary, forming months to years after an injury
Testing for Hypertrophic Scarring
The diagnosis of a hypertrophic scar or keloid is typically determined based on a physical exam. However, if the scar keeps worsening or changing, a biopsy might be needed, which is a procedure to collect a small sample of the scar tissue for testing. Hypertrophic scars stay within the area of the original wound or injury while keloids grow larger than the original wound. It’s also worth noting that there’s a theoretical increased risk of keloids turning cancerous compared to hypertrophic scars, although this is not a common occurrence.
Treatment Options for Hypertrophic Scarring
Good surgical technique is key to preventing overgrown scars, also known as hypertrophic scars, during surgery. People who are prone to forming these kinds of scars or similar ones called keloids should avoid procedures that are not medically necessary.
Once a hypertrophic or keloid scar develops, several different treatment options can help. One common method is an injection of a corticosteroid, a type of medication, into the scar. Surgery can also be used to remove these scars. For keloid scars, it’s important to combine surgery with another treatment like corticosteroid injections or radiotherapy, a form of cancer treatment that uses high-energy rays, to be more effective. Radiotherapy can treat and even prevent keloid scars. Laser therapy can also successfully treat hypertrophic scars. Different lasers can target the blood vessels in scars, helping to reduce the noticeable color changes associated with hypertrophic scars. There’s also cryotherapy, a treatment that involves freezing the scar. While this process may destroy tissue and seem counterproductive, experts believe it triggers a different biological response than other injuries like burns and can help in the treatment. 5-Fluorouracil, a type of chemotherapy drug, has been successful in treating and preventing keloid scars as well.
Treating burn wounds and avoiding the formation of hypertrophic and keloid scars after a burn injury can be challenging. Burn wounds are classified as either superficial or deep. Superficial wounds typically heal without developing any hypertrophic scarring. For deep wounds, the typical method of treatment is to surgically remove the burned area and replace it with a graft of the patient’s own skin. Laser therapy is often used to treat the hypertrophic scars that can result from burns. The therapy can improve the color and height of the scar, and even relieve symptoms like pain and itchiness. While compression therapy, which involves applying pressure to the area, was traditionally used for managing burn wounds, research has shown it doesn’t really affect the development of hypertrophic scars. Good nutrition and vitamin supplements are recommended for burn patients or those with chronic wounds. As medical science advances, future treatments for managing burn wounds may include therapies that target certain molecular pathways, which are basically interactions among different substances within our cells that enable cells to function.
What else can Hypertrophic Scarring be?
Usually, hypertrophic and keloid scars are identified just by looking at them. However, in some cases, especially in ones where these scars continue to change or grow, a biopsy might be needed. This is a simple test where a small sample of the scar is taken and examined under a microscope. It’s also important for doctors to consider other conditions that can look similar to hypertrophic scars or keloids. This could include:
- Sarcoma, a type of cancer that starts in tissues like bone or muscle
- Dermatofibrosarcoma protuberans, a rare skin cancer
- Dermatofibroma, a small and harmless bump that appears on the skin
- Nodular scleroderma, a skin disorder leading to hard, tight skin and other problems
- Infections like lobomycosis, a long-term fungal infection
