What Is a Hypertrophic Scar

Hypertrophic scars result from an abnormal inflammatory response (the immune system's reaction) to an injury, causing excess scar tissue growth. A skin injury through the dermal (inner) layer or deeper sets the body's natural inflammatory response in motion to heal the injured skin. The result of this healing process is a scar.

In some people, the inflammatory response causes excess fibrinogen (a protein that helps with blood clotting) and collagen (a protein that supports your skin). When this occurs, the scar can overgrow, which is known as hypertrophic scarring.

This article discusses what hypertrophic scars are, what causes them, and treatment options for scars that do not resolve independently.

What Causes a Hypertrophic Scar?

Scarring is your body's response to skin wounds penetrating the skin's dermal layer or deeper. Although poorly understood, hypertrophic scars are considered an abnormal inflammatory response to a skin injury.

Hypertrophic scars begin developing within weeks after an injury. They appear raised above the skin and usually flatten over time. They typically form on the chest, upper back, or shoulder area but can occur anywhere.

During the healing process, excessive collagen and fibrinogen cause the scar to overgrow within the boundary of the original injury, causing a hypertrophic scar. Injuries to the skin that go deeper than the dermal layer and can cause hypertrophic scarring include:

• Burns
• Chicken pox lesions
• Insect bites
• Piercings
• Surgical scars
  
• Tattoos
  

Appearance

Although not as complex or challenging to treat as keloid scars (abnormal scars that grow outside the original injury site), hypertrophic scars have some distinct characteristics. They may:

• Develop within the injury or wound location
• Be raised, red, and uncomfortable
• Become wider over time
• Appear hyperpigmented (darker than your skin color) or hypopigmented (lighter than your skin color)
• Flatten out and resolve within several weeks to months

Hypertrophic Scar Treatment

Hypertrophic scars typically resolve on their own within several weeks to months. However, depending on their location, they may cause discomfort or inhibit free movement and, thus, require treatment.

There are various methods to treat a hypertrophic scar. Working with a healthcare provider, such as a dermatologist or plastic surgeon trained in these treatment modalities, is important to ensure an optimal outcome.

First-Line Treatments

The most common first-line treatment options include:

• Cryotherapy: This method freezes the scar to break down scar tissue slowly. It may cause hypopigmentation or discomfort but is a routine treatment.
• Intralesional corticosteroid injection: Typically inexpensive and easy to perform in a qualified healthcare setting, long-acting corticosteroid injections can fully resolve a hypertrophic scar. This treatment modality usually requires multiple injections and can cause some discomfort.
• Silicone sheets: Silicone gel sheets reduce the size, hardness, redness, stiffness, or discomfort associated with hypertrophic scars. For best results, cover the scar with an optimally sized silicone gel sheet every day for several months.
• Pressure therapy: Pressure therapy is the application of pressure to a wound during the healing process using an elastic bandage or stocking, which makes this an inexpensive treatment option.
  

Second-Line Treatment

If none of the first-line treatment options are successful in eliminating a hypertrophic scar, a healthcare provider might recommend a second-line treatment option, such as:

• Laser treatment: Although not fully understood, researchers have identified that laser therapy minimizes hypertrophic scarring, decreasing the scar's redness and allowing for better movement by breaking down hypertrophic scars.
• Surgical excision: A qualified healthcare professional, such as a dermatologist or plastic surgeon, would surgically remove the excess collagen creating the hypertrophic scar. Depending on the size of the scar, a provider may use healthy skin from another area of the body to replace damaged skin, known as a skin graft.

For optimal results, your healthcare provider may recommend surgical excision combined with intralesional corticosteroid injections and other first-line treatment options to prevent continued scarring during the postsurgical healing process. This combined treatment method is expensive and extends the overall healing time.

How Long Does Hypertrophic Scarring Last?

Hypertrophic scars begin forming between one week and a month after a skin injury and may take over a year to heal. The time it takes for your hypertrophic scar to recover depends on the following factors:

• Age
• Genetics
• Hormones
• Immune response
• Race

The appearance of hypertrophic scars typically improves over time, but this can be slow. The final appearance of a scar is determined by the following:

• Skin type and location on the body
• Wound direction
• Injury type (e.g., burn, injury, surgery)
• Age
• Nutritional status
  

Summary

Scarring after a skin injury is part of the body's healing process. A hypertrophic scar occurs when excess collagen and fibrinogen build up at the injury site during healing. The resulting hypertrophic scar can be raised, red, uncomfortable, and potentially limit movement. Though they generally flatten out and resolve within weeks to months, hypertrophic scars that cause pain or limit movement can benefit from treatment.