Scars and Scar Tissue: Causes, Problems, and Possible Treatments

Scar tissue forms in injured areas of our bodies and replaces cells that have been destroyed. It appears either inside the body or on its surface and is a normal part of the body's healing process whenever we have a significant injury. Scar tissue acts as a barrier and protects the place that was injured, but it unfortunately lacks the functionality of the original tissue and has low elasticity. On the surface of the body it may be a cosmetic problem or even be disfiguring.

Scar tissue on our skin looks different from the surrounding area and is usually referred to as a “scar". Some people develop hypertrophic scars on their skin. These are larger than normal and have a lumpy appearance. Keloid scars are raised and spread beyond the wound. Atrophic ones are sunken and form depressions in the skin. Inside the body, scar tissue in the form of adhesions or fibrosis may cause problems.

Scar tissue is made of fibrous connective tissue. This tissue supports and connects body structures and holds them in place. It contains fibres made of a protein called collagen. It also contains cells called fibroblasts, which make the collagen, as well as water and carbohydrates.

Fibrous connective tissue is sometimes known as dense connective tissue because the collagen fibres are densely packed and there are comparatively few cells present. It's a normal component of the body and is present in uninjured areas. Researchers have discovered that the connective tissue in scars has a slightly different structure from the normal form.

Causes

Scars may be caused by wounds such as burns, surgical incisions, physical injury, chemical injury, infections, diseases, inflammation, and acne. Not all wounds cause scars. There must be significant damage to the body before the formation of scar tissue is triggered. Some people tend to form scars more easily than others, however.

Appearance

Scars on the skin are red when they are first made due to an increased blood flow as the wound heals. Over time, the blood supply decreases and a scar becomes paler. It may take many months or even years to reach its final form. Scarred areas are generally thicker than their surroundings and lack hair, sweat glands, and melanin (the pigment that protects the skin from ultraviolet radiation).

The first structure that forms in a wound is the blood clot, which prevents blood loss. The clot may be replaced by scar tissue. Scarring can be reduced by making sure that the edges of a wound are brought close together during the healing process. When the edges of a wound gape, scar tissue may be formed to fill in the gap.

Good wound dressings, good nutrition, and appropriate medications (such as antibiotics) can help to protect and defend an injured area. The amount of scarring and the final appearance of a scar depend mainly on genetics and age, however. Older people tend to scar more easily than younger people. Their bodies may not make enough of the normal skin cells needed to replace the ones that have died.

Although we can discourage our body from producing scars, it's hard to completely avoid the process. Surgeons are well aware of the body's tendency to scar. They often try to make their incisions in a direction or a place that will minimize scarring or that will minimize its visibility.

Hypertrophic

In a hypertrophic scar, too much collagen is made. The scar forms a raised area or lump above the wounded area of the skin. The lump is often pink in its early stages and may be itchy.

Keloid

Keloid scars grow beyond the wound, forming a reddish tumour. This tumour is benign (not cancerous) and consists mainly of collagen. Keloid scars may form as a response to injury, but in some people they form spontaneously with no known cause. They may be itchy and create a burning sensation.

Atrophic

Atrophic scars look like pits in the skin and may be formed during problems such as acne and chicken pox. In this type of scar, the body doesn't make enough connective tissue to fill in the wound.

In general, scars on the skin can’t be completely removed once they form, but they can be treated to make them less noticeable. The improvement in appearance may be very significant. Treatments generally require weeks or months to be effective, however. Most scars fade to some extent on their own as time passes.

Some treatments that may be recommended include the following.

• Pressure applied to a scar or silicone sheets placed over the area often improve its appearance. These treatments flatten raised scars and make scars paler.
• Doctors may inject corticosteroids into a raised scar to inhibit collagen synthesis and reduce inflammation.
• Surgical techniques can remove some scars, but the body may make a fresh scar as it heals itself from the surgical wound. The new scar may look better than the old one, however.
• In dermabrasion, the surface layer of scarred skin is removed in an abrasive process. Laser surgery can be used to remove the raised surface of a hypertophic or keloid scar.
• A different type of laser treatment can improve the appearance of acne scars. The treatment stimulates the formation of new collagen, which partially fills in the pitted areas.
• Skin grafts may be used to cover some scars, such as those created by burns.

Causes

As a result of trauma, fibrous bands or sheets may form inside the body. These bands are known as adhesions because they join structures or different parts of the same structure together. Adhesions arise due to the inflammation caused by conditions such as surgery and infections.

Another type of internal scar tissue is fibrosis, or the buildup up of excess fibrous connective tissue in a particular location in the body. Fibrosis may occur inside organs. Sometimes the cause of the fibre buildup isn't known, but in other cases it appears after an injury and acts as scar tissue.

Scar tissue production in the heart may be caused by a heart attack and the accompanying death of heart muscle. Cirrhosis of the liver, a condition in which the normal liver tissues are gradually replaced by scar tissue, may result from excessive alcohol consumption, a hepatitis C infection, or obesity.

Effects

Adhesions often cause no symptoms, but they sometimes produce pain and other problems. They may cause organs to change their shape or move out of their correct positions. They may also prevent the movement of a structure that should be moving.

Scar tissue in the heart may increase the chance of an irregular heartbeat (arrhythmia) because the damaged tissue interferes with the electrical signal that triggers the heartbeat. The liver has many vital functions. Cirrhosis of the liver is a very serious condition, since the scar tissue can’t perform the liver’s normal jobs.

Adhesions may improve on their own. They can also be removed surgically. There is a risk that new adhesions will develop after the surgery, however. Doctors sometimes place a thin barrier material around an organ during surgery. The barrier prevents the attachment of adhesions and eventually dissolves.

Doctors do have some techniques for dealing with scar tissue in hearts, livers, and other organs, but extensive scar tissue is often hard to manage. Cirrhosis of the liver is especially serious. Once the process starts, the replacement of liver tissue with fibrous tissue is progressive. It's much easier to prevent cirrhosis than to treat it.

Scar tissue formation in our bodies is often unavoidable, but the good news is that there are steps that we can take to prevent or reduce the process. Proper wound treatment and a healthy lifestyle can decrease the probability of scar tissue formation or decrease the amount that's made.

If scars do form, medical treatments can often improve their appearance and even remove some of the scar tissue. Makeup can hide many skin scars that can't be completely removed. In addition, clinical trials are being performed to test new treatments that may be more effective than the current ones.

• The National Institutes of Health has created a webpage containing information about different types of scars. The page contains a link to a list of clinical trials of new treatments.
• The Columbia University MedIcal Center also has a webpage with information about types of scars and their treatment.