Scars: Definition, Types, Removal, and Treatment

General

Scars Definition and Meaning:

The negative impact of scars, those inevitable consequences of injury, disease, and surgery affect billions worldwide. But their definition and meaning remain poorly understood amongst most people. Scar tissue is best understood as a localized collection of a substance called collagen that is deposited by the body at the site of a wound. Scars are necessary to mend damaged skin, but in so doing, often created problems of their own.

Collagen

Once skin is injured, the wound healing process begins immediately. Around day 5, specialized cells called fibroblasts begin to produce and deposit collagen into the gaps between skin edges. Filling of the wound with collagen ultimately mends the damaged skin in the same way that cement is used to fill in a crack in the sidewalk. It is the amount of collagen laid down in the wound, as well as its color, and texture that determine what a particular scar will look like. A minimal amount of skin-toned collagen is ideal and produces a scar that is fine, flat, and blends beautifully into the surrounding skin. Too much collagen, and one that is raised, wide, and discolored can be the result. Collagen that stretches over time can lead to a flat, overly wide scar.

3 variations of human scars differing in thickness and width
From left to right, scars (animated) of decreasing thickness resulting from variable amounts of collagen deposited during wound healing

PREDICTING HOW YOU WILL SCAR IS A MAJOR CHALLENGE BECAUSE OF THE NUMBER OF FACTORS THAT CONTRIBUTE TO FINAL RESULTS

Types:

Practically speaking, there is no such thing as “scarless” healing. A simple way to understand the different types of scars is by classifying them as normal and abnormal.

Normal Scars

Normal scars are the types both patients and surgeons strive to see. This type of scar is the closest we can ever get to “scarless” healing. Normal, mature scars are fine, flush to the skin, blend well, and are minimally visible overall. Notably, even the best scars usually looked angrier, redder, and possibly even raised within the first few months of healing. Over 12-24 months, these normal, mature scars gradually flatten and lighten. This rather long maturation process during which the scar improves dramatically explains why it takes time to know exactly how it will turn out. It’s also why significant interventions are not recommended for at least the first 12 months after surgery.

A skin scar that is normal, fine and blends well into skin
Normal, fine and subtle skin scar

Hypertrophic Scars And Keloids

Keloids and hypertrophic scars are thick, raised, and discolored. They result from the over-deposition of collagen during the healing process. With these, healing seems to get “stuck” in the phase of healing during which collagen is produced – something like a water tap that’s stuck in the on position overflowing a bathtub. Keloids and hypertrophic scars can be itchy and painful and many people find them very difficult to cope with. The severity of the impact that they have on peoples’ lives is hard to overstate. It is therefore imperative that their cause and potential preventative measures be understood well by patients prior to undertaking elective surgical procedures.

Hypertrophic thick scars of the lower abdomen
Hypertrophic, thick, and raised scar on the abdomen. Note that the scar remains more or less on the incision line
A large protruding keloid scar of the right elbow
Keloid scar on the elbow. Unlike with hypertrophic scars, the scar extends far beyond the borders of the skin injury.

Hypertrophic And Keloid Scars: Similar, But Very Different

The substantial overlap in risk factors, appearance, and behavior between hypertrophic scars and keloids can make them difficult to distinguish by patients and even by experienced doctors. While hypertrophic scars and keloids share much in common, there are also some key differences between the two. One significant difference is that hypertrophic scars more or less stay within the boundaries of the incision or injury that created them. Conversely, keloids grow far outside of the incision line, behaving more like a growing tumor than a scar. Moreover, hypertrophic scars often improve over the first year, while keloids rarely do, and often get worse with time. Here are some of the differences between hypertrophic and keloid scars:

Hypertrophic ScarKeloid
more commonless common
from a wound or incisionfrom a wound, incision, or even a trivial injury like acne, piercing, or bug bite, sometimes seem “spontaneous”
usually seen a few months into healingcan arise many months or even years after a wound
extend minimally beyond borders of initial wound or incisioncan extend greatly beyond borders of the initial wound or incision, showing almost tumour-like growth
generally improve over first yearrarely improve over time, often get worse
often occur over joints, high tension areascommonly on upper back, earlobes, neck, knees, shoulders, face, upper limb
can be itchy, usually not painfulcommonly itchy and painful
all skin tonesstrongly associated with darker skin tones
weaker genetic associationstronger genetic association
often improve with surgical revisionrecurrence rate is extremely high, can recur even larger than the original keloid

Wide Scars

These typically start out flat and of normal width but become wider with time. They ultimately becoming wide, flat, and pale. Wide-spread scars are most common in areas of constant motion such as the knee, shoulder, and upper back. “Stretch marks” are a particular type of wide-spread scar. Many patients do not find wide-spread scars as distressing as keloids and hypertrophic variations due to their more subtle, less aggressive look. But if a wide-spread scar occurs on a cosmetically important area such as the face it can be a real aesthetic concern. Therefore, understanding, anticipating, and ultimately preventing them is worthwhile for all surgical patients.

A widespread flat and pale scar of the skin
Wide-spread scar showing typical stretched, flat, pale appearance

Pigmented Scars: Too Dark Or Too Light

Healing incisions are prone to pigmentary abnormalities that can contribute to an undesirable aesthetic appearance of scars. Both hypo-pigmentation (too light) and hyperpigmentation (too dark) are commonly seen. These discolorations can make scars that have otherwise healed well far more conspicuous. In general, individuals with darker skin tones and larger wounds that are not closed surgically such as with stitches or skin staples are more prone to pigmentary abnormalities. Wounds that become infected, or open prior to healing are also more susceptible to abnormalities in pigmentation. Ensuring wounds heal in a complication-free manner is critical to avoid abnormalities in pigmentation. Healing areas should also be carefully protected from the sun for at least the first year after surgery. Direct sun exposure in the first year can darken scars permanently, making them more noticeable.

Hypo-pigmented skin scars are lighter than the surrounding skin
Hypo-pigmented scar that is lighter than surrounding skin
A patch of hyper-pigmented, dark scars on the skin
Hyper-pigmented scars from acne that are darker than the surrounding skin

Scar Removal, Scar Prevention, and Scar Treatment:

Scarless healing, prevention, and scar removal remain amongst the holy grails of medical science. Practically speaking, there is no such thing as “scarless” healing or complete removal. Whenever someone describes surgery or a wound that “didn’t leave a scar”, the truth is that one is present but barely visible. While the goals of scarless healing and total prevention have yet to be achieved, major progress has been made in this area in recent decades.

Prevention

The first step in effective scar prevention is understanding what type of scars you are most likely to form because different scar types have different approaches. Scarring likelihoods are very difficult to predict in many cases because of the large number of complex factors that contribute to overall scar results from injury or surgery. Preventative measures for different types of scars are summarized here:

Everyone Should Do These To Optimize Scarring:

AdviceReasoning
adhere to all after-care instructions carefullyany healing complication can lead to poor scarring
don’t return to physical work or exercise too earlycan lead to stitches opening or infection
use sunscreen as soon as the wound is healed (consistently for 1 year)
sun exposure can permanently darken scars
silicone gel or silicone strips for 3 monthsproven to help prevent thicker scars

If You’re Prone To Hypertrophic Scars:

AdviceReasoning
adhere to all after-care instructions carefullyany healing complication can lead to poor scarring
use sunscreen as soon as the wound is healed (consistently for 1 year)sun exposure can permanently darken scars
prolonged use of silicone gel or silicone strips for 6 monthsproven to help prevent thicker scars with prolonged use
pressure devices such as compression earrings after ear-piercing for 3-12 monthssoftens and flatten scars
consider cortisone injections if not improving by 6-12 months (as per the advice of your doctor)a cornerstone of hypertrophic scar prevention

If You’re Prone to Keloid Scars:

AdviceReasoning
adhere to all after-care instructions carefullyany healing complication can lead to poor scarring
use sunscreen as soon as the wound is healed (consistently for 1 year)sun exposure can permanently darken scars
prolonged use of silicone gel or silicone strips for 6 monthsproven to help prevent thicker scars with prolonged use
pressure devices such as compression earrings after ear-piercing for 6-12 monthssoftens and flatten scars
cortisone injections as soon as the wound is healed or even during the procedure consider cortisone injections if not improving by 6-12 months
(as per the advice of your doctor)
a cornerstone of keloid scar prevention
Botox injections (botulinum type A toxin) reducing muscle tension can help prevent thick scarring
less common options are injections of 5-FU, verapamil, and bleomycin all have been shown to help prevent thick scarring

If You’re Prone To Wide-Spread Scars:

AdviceReasoning
early and prolonged supportive taping with products such as Steri-Strips andsupports the wound edges to help prevent scar widening

Treatment And Removal Of Scars You Already Have

Hypertrophic Scars:

AdviceReasoning
prolonged use of silicone gel or silicone strips for as long as improvement is occurringproven to improve even scars that have been present for years
cortisone injectionssoftens and flatten scars
surgical scar revision if still problematic at 1 year, followed by preventative measuresremoves scar completely; goal becomes preventing recurrence

Keloids:

AdviceReasoning
prolonged use of silicone gel or silicone strips for as long as improvement is occurringproven to improve even scars that have been present for years
cortisone injectionssoftens and flatten scars
less common options are injections of 5-FU, verapamil, and bleomycinall have been shown to help improve thick scarring
Botox injections (botulinum type A toxin)reducing muscle tension can help improve thick scarring
lasersoftens scars and reduces discoloration
surgical scar revision if still problematic at 1 year, followed by aggressive preventative measuresremoves scar completely; goal becomes preventing recurrence
radiationpowerful modality, usually used after surgery, many potential side effects
so used only in severe cases

Wide Scars:

AdviceReasoning
surgical scar revision early and prolonged supportive taping with products such as Steri-Strips andremoves scar completely; goal becomes preventing recurrence

Summary:

There are wide variations in scar type and quality formed between individuals. This makes the anticipation of results from lacerations, surgery, and even simple ear-piercings a huge challenge. It is also not uncommon for one person to heal very differently on different body areas. Moreover, even the best surgeons have patients who have scarred poorly in their practices because surgical technique is only one of many factors that contribute to a patient’s results. Personal characteristics such as genetics, skin tone, and many others all play a role in every person’s innate scarring tendencies. Attempting to decipher how all of these factors will interact remains a challenge for doctors and patients alike.

Medical References:

Mokos, Zrinka Bukvić et al. “Current Therapeutic Approach to Hypertrophic Scars.” Frontiers in medicine vol. 4 83. 20 Jun. 2017, doi:10.3389/fmed.2017.00083

Gauglitz GG, Korting HC, Pavicic T, Ruzicka T, Jeschke MG. Hypertrophic Scarring and Keloids: Pathomechanisms and Current and Emerging Treatment Strategies. Mol Med. 2011;17(1-2):113-125. doi: 10.2119/molmed.2009.00153

Rockwell W. B., Cohen I. K., Ehrlich H. P. (1998). Keloids and hypertrophic scars: a comprehensive review. Plast. Reconstr. Surg. 84 827–837. 10.1097/00006534-198911000-00021

Chadwick, Sarah et al. “Abnormal pigmentation within cutaneous scars: A complication of wound healing.” Indian journal of plastic surgery : official publication of the Association of Plastic Surgeons of India vol. 45,2 (2012): 403-11. doi:10.4103/0970-035

Ziolkowski, Natalia et al. “Psychosocial and quality of life impact of scars in the surgical, traumatic and burn populations: a scoping review protocol.” BMJ open vol. 9,6 e021289. 3 Jun. 2019, doi:10.1136/bmjopen-2017-021289

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