Understand How Scars Form

Understanding the structure of the skin and the pathology of scars is essential to know what scars are and how they develop.


The skin is the largest organ of your body and holds many important functions.  Skin protects us from microbes and the elements, helps regulate body temperature, and allows us to feel touch, heat, and cold.

Skin Has Three Layers


The outermost layer of skin, provides a barrier to the elements.


Beneath the epidermis, contains tough connective tissue, hair follicles, and sweat glands.


Deeper subcutaneous tissue made of fat and connective tissue.

The Main Functions of the Skin Are:


Acts as a barrier and protects us from bacteria, viruses and fungi.


Has sensory receptors (nerves) react to external stimuli.

Metabolic Activity

Absorbs different things like lotions, and UV light from sun (which generates vitamin D). It also has a detoxifying function as the body can eliminate products through the sweat.


Regulates body temperature.


When the skin is damaged the body produces special cells to repair it. Scars are the sections of repaired skin that do not look like natural skin even after they are healed. Scars are part of everybody’s life and millions of new scars are formed year after year. Understanding the structure of the skin and the pathology of scars is essential to know what scar are and how they develop.

Abnormal or Problematic Scars

In some cases, scars can become problematic or abnormal. They do not heal to become a fine line but remain visibly different to the surrounding skin in size, color, contour and texture. Several varieties of abnormal scars exist and include types such as hypertrophic scars and keloids.

Some scars have too much collagen and other tissues, which causes raised skin. Some have too little collagen, which causes the scar to be lower than the skin around it. Repaired skin might have no hair follicles, be less elastic (or flexible), and form longer strands of tissue compared to the skin around it. These changes create different types of scars.

The General Scar Formation Process

A scar is a permanent mark on your skin left by a healed wound. It is the result of the normal wound healing process after skin tissue is injured. The body produces collagen to reconnect tissues which are broken apart by an injury. Scars consist of flexible and strong collagen tissue which is formed during said repair process of the skin. Immature scars can have a reddish colour and are usually raised, itchy and might be slightly painful.

A normal mature scar develops later on during the maturation phase. The scar will become flattened and more pale in colour, e.g. white or silver, but it will not fully disappear. You will be left with a mark on your skin. The whole scarring process can take up to 2 years to conclude.

What Causes Scars?

Scars can occur from any damage to the skin, but they can be worse if any scabs that form are removed too early. A number of other events or conditions can cause scars.

After you injure yourself, the wound will be slightly red and warm due to the instant reparation process initiated by your skin. After a while you will develop a scab which protects the wound while it is healing. Eventually this scab falls off and you might or might not be left with a scar. The highly complex reparation process of your skin can be categorized into three main phases: inflammation phase, proliferation phase and maturation phase.

The Three Stages of Scar Formation


Inflammatory Phase

The body’s first response to an injury is the inflammatory phase. The blood vessels in the wound bed contract and a blood clot is formed. Once the bleeding has stopped the blood vessels dilate again to let mostly white blood cells, and other essential cells pass through to reach the wound. There they start to repair the damaged tissue.

This stage is where you can observe the typical signs of the inflammatory phase: a reddened skin (erythema), heat, oedema and pain. A scab, or crusty area, forms on top of the wound within the first few days. Removing scabs too early can cause more skin damage and cause larger scars.

Proliferation Phase

The proliferation phase follows shortly after the inflammatory phase, usually within hours after an injury and continues for three to 14 days. This is where the wound is repaired with so called granulating tissue which mostly consists of collagen. Fibroblasts are the active cells that produce the flexible and tough collagen fibers to provide strength and structure within the granulating tissue.

Blood vessels also form in this newly built tissue and bring oxygen and nutrients to the cells in the reconstructive work and remove waste products from the wound. At this stage, the epidermis begins to close on top of the wound. In addition to this, the edges of the wound are gradually being pulled together and the wound becomes smaller.


Maturation Phase

About 3 weeks after the proliferation phase the maturation or remodeling phase begins. Water begins to gradually leave the scar, and collagen fibers begin to lie closer together. This process makes the wounded skin stronger. After about two months, the area of the wound will be about as strong as it can be, which is about 80 percent as strong as unwounded skin.

This phase of healing can continue for months or even years. It’s the longest and final phase of the wound healing process and can take up to two years to conclude. The capillaries (blood vessels), which are no longer needed, begin to thin out. The collagen of the proliferation phase is replaced by a much stronger type of collagen and the wound continues to contract. At the end of the maturation phase the wound is permanently sealed with collagen scar tissue which has little of the cell activity present than regular skin.

Types of Scars


These are light in colour and flat.


These scars appear red, are sometimes itchy and painful, and slightly elevated. Many will mature to become flat and assume pigmentation similar to the surrounding skin. They can be more pale or slightly darker.

Widespread Stretched

These appear when the fine lines of surgical scars gradually become stretched and widened. Typically flat, pale, soft, symptomless scars are often seen after knee or shoulder surgery. Stretch marks after pregnancy are variants of widespread scars. No elevation, thickening or nodularity which is present distinguishes them from hypertrophic scars.

Linear Hypertrophic

These scars are red, raised and sometimes itchy. Confined to the border of the original surgery or trauma. These scars develop within weeks after surgery and may increase rapidly in size for three to six months and then, after a static phase, begin to regress. They mature to have an elevated, slightly rope-like appearance with increased width. Full maturation can take up to two years.


Scars that cross joints or skin creases at right angles are prone to develop shortening or contractures. They occur when the scar is not fully mature and tend to be hypertrophic. They typically have disabling and dysfunctional properties. They result mostly from burn injuries.

Widespread Hypertrophic

Common after a burn. A widespread red, raised and sometimes itchy scar that remains within the borders of the original burn.

Minor Keloid

A focally raised, itchy scar that extends over normal tissue. May develop up to several years after injury and does not regress without treatment. Surgical excision is often followed by recurrence.

Major Keloid

A large, raised scar which may be painful or pruritic. Extends over normal tissue and can continue to spread over many years.


Atrophic scars occur as depressed and well-defined lesions. They are usually caused by collagen destruction during the course of an inflammatory condition such as cystic acne or varicella. These scars often have a sunken and pitted appearance.