Hypertrophic Scars and Keloids

The information in this section is made available through the generous support of Dr. Grant Stevens.

"Normal scarring vs. hypertrophic scarring"

The epidermis or epithelium of the skin is the only structure of skin that can regenerate.  Regeneration is a process of rebuilding the original structure to its original condition - by definition, without scarring.  Any injuries to the dermis (or lower part of the skin) such as incision, burn, or other trauma heal through "repair," which results in a scar.

Many injuries to the dermis heal so cleanly that no discernible scar is apparent.  However, some injuries scar in a more dramatic fashion resulting in hypertrophic scars or keloids.  Several factors impact the formation of hypertrophic scarring including genetic predisposition, skin color (darker skin), the location of the injury, and others.  Areas under relatively high pressure, such as the presternal area (especially when the incision travels vertically), near the armpit or shoulders are predisposed to hypertrophic scarring.

What are hypertrophic scars or keloids?

In the normal repair process of injury to the dermis, elevated levels of collagen are delivered to the wound site to heal the injury.  After this process, collagen is continuously deposited while older collagen is continuously broken down by the body, resulting in a normal scar response.  In hypertrophic scars, the body continues to deliver collagen, which is deposited in a disorderly fashion, while the normal process of collagen lysis, or breakdown, is suspended or impaired.

It is a myth that fair skinned people do not develop hypertrophic scarring. In the past 15 years we've seen an equal distribution of hypertrophic scarring across our membership, regardless of skin color.

Hypertrophic scars are typically raised, erythematous (red, pink, or purple) and stiffer than the surrounding skin.  Over time most hypertrophic scars mature resulting in a scar remnant that appears like that of a normal scar except it is typically wider than if the scar had not become hypertrophic.  Note that when an incisional wound heals normally, the resulting scar remnant may be as fine as a simple pencil line across the skin, while the matured hypertrophic scar may appear wider, like that left by a pencil eraser.  Hypertrophic scars often are associated with hypersensitivity to touch (like clothing sliding across the skin), and they may itch or be generally painful. They can often feel as though they are adhered to the surface below, making movement painful.

Keloids have been described as hypertrophic scars on steroids!  By definition, a hypertrophic scar remains within the boundaries of the original injury while a keloid may grow beyond those boundaries.  Also, while hypertrophic scars typically regress over time, keloids generally do not.

Because the distinction between hypertrophic scars and keloids is often unclear, the medical literature and medical professionals often use the terms interchangeably.


Intralesional Steroid Injections

Steroid injections have been a mainstay in therapy for keloids and hypertrophic scars.  The mechanism of action is that the steroid inhibits fibroblast growth, reducing the amount of collagen deposited into the scar.  Side effects include hypopigmentation (less than normal skin pigmentation compared to the surrounding skin), atrophy, and telangiectasias.  Recurrence is common in some studies, but steroid injection is generally considered effective for scar reduction.


Cryotherapy has been reported as an adjunct to steroid injection and used independently.  Use in combination with steroid injections may be more effective than when used independently.

Topical Silicone Sheeting

Silicone sheeting has been documented in the medical literature for hypertrophic scar prevention and reduction since 1982.  Used originally in burn centers for burn scars, this technology offers non-invasive, pain-free therapy with low side effects.

The mechanism of action remains unproven, but it is hypothesized that by maintaining a high level of hydration in the stratum corneum (part of the dermis), keratinocytes and fibroblasts interact differently to reduce the production of collagen.  Studies have demonstrated that silicone sheeting does not affect oxygen tension in the skin, increased pressure, or silicone oil in the local skin environment - all earlier theories for why silicone sheeting may affect scars the way it does.

In one study, 20 women who underwent breast reduction surgery were enrolled into a study where the incisions of one breast were treated with silicone sheeting, while the other breast was left untreated as the control.  The study found that 25% of the treated wounds developed hypertrophic scars while 60% of the untreated wounds developed hypertrophic scars.  The effects were still present at 6 months with only 2 months of application.

Side effects of silicone sheeting are generally mild.  When applying silicone sheeting to very fresh scars, some patients may experience some breakdown of the affected tissue.  Other may experience contact dermatitis (or sweat rash).  In each case, usage should be discontinued until the symptoms resolve.  In the case of contact dermatitis, patients should be sure to clean the silicone sheeting and underlying skin thoroughly on a regular basis to prevent this effect.

Silicone sheeting should be used for 12 - 24 hours per day up to 12 weeks.

Steri Strips

We have seen great results simply by using steri strips, and those results appear to be very close to using expensive silicone sheeting. The action is about the same. The thought is that keeping air off the incisions inhibits over-production of collagen, the action that causes scars to over-grow. If you are not allergic to steri strips, we can teach you how to effectively use steri strips in your scar care from very early on in your recovery.


An onion extract product used to ameliorate scars, Mederma was found to be ineffective in one small study when used for 1 month.  Another study comparing Mederma to placebo found no effect on scar size or appearance. Some patients reported a subjective improvement in scar softness with Mederma. However, our overall experience with members over the course of nearly 15 years here at BreastHealthOnline is that this really isn't very effective at all, and many people seem to develop allergic reactions to it. As a result, we don't recommend Mederma at all.

Aloe Vera

No available medical literature has demonstrated the effectiveness of Aloe Vera for hypertrophic scar prevention or reduction.

Vitamin E

A double-blind study with 15 patients evaluating the topical application of vitamin E on surgical scars found no improvement in the vitamin E group.  The study found 33% of the patients using vitamin E developed skin reactions.

Pulsed-Dye Laser

A series of studies suggest that the pulsed-dye laser (PDL) appears to be a very promising tool for treating hypertrophic scars and keloids.  The mechanism of action is unclear; however, it is known that this laser targets vascular structures.  It is hypothesized that by destroying the smallest blood vessels, localized reduction of oxygen may stimulate collagenase (which breaks down collagen).  Also, by heating the collagen, remodeling of the scar may be hastened.

Studies demonstrated improvement in the scar with 1 - 3 laser treatments.

Please Note:

Part of the information provided above was referenced from "Treatment of Hypertrophic Scars and Keloids: A Review" written by Erick Mafong, MD and Robin Ashinoff, MD, published in Aesthetic Surgery Journal in its March/April 2000 edition.  For footnote information and greater detail, please reference this article.