Dermatologists at NYU Langone determine the type of scar by evaluating its size, location, and texture during a physical exam. Scar tissue, which consists of a tough, fibrous protein called collagen, forms when the body repairs a wound. Common causes of scars include injury, surgery, and infection. As scar tissue begins to form, it may appear red, raised, and hard, but over time it fades, flattens, and softens.
Depending on the type of injury, the depth of the wound, and the person’s skin type, this process takes months. It may take a year or more for a scar to fully heal.
With the exception of very superficial injuries, such as a shallow paper cut, all skin wounds result in some type of scar. However, not every person’s skin forms scar tissue in the same way.
If the skin creates excessive amounts of collagen while it heals, the result is a thick, widened, and sometime raised scar that remains within the boundary of the injury. This is called a hypertrophic scar. Sometimes scar tissue grows over the boundaries of the original wound, creating a puffy, round protrusion called a keloid.
Hypertrophic scars and keloids may be itchy, tender, or painful. These unusual scars may occur as a result of genetics—they sometimes run in families, and typically, if one forms after an injury, it forms after your subsequent injuries, too. But why they form in some people and not others isn’t known.
People may not realize they have a predisposition to hypertrophic scars or keloids until they notice the scars forming as the result of an ear piercing or a tattoo.
Scars may also form as a result of skin trauma caused by acne or burns. Pitted acne scars, also called atrophic scars, may have a sunken appearance that makes the surface of the skin look pocked or uneven. An infection such as the chicken pox can also cause atrophic scars.
Burn scars, which are called contracture scars, are often flat and shiny and may cover a large area of skin. Depending on how badly the skin was burned, this type of scar may affect muscle and tissues below the skin.
Stretch marks are another type of scar. They develop as a result of rapid skin expansion during pregnancy, weight gain, and growth spurts. Stretch marks may also appear if a wound is located above a joint, such as the knee or elbow, if repeated movement of the skin during healing causes the scar to look elongated or striated.
A dermatologist examines your skin to determine what type of scar you have. He or she makes note of its location and size because scars may have different characteristics depending on where they are on the body. For instance, if a scar on the face or hands is exposed to sunlight, it may become permanently discolored.
Wounds in parts of the body with lower blood flow, such as the leg or foot, may take longer to heal than those in areas where blood circulation is more robust, such as the face or scalp.
During a physical exam, your dermatologist may ask you questions about what your skin looked like after previous injuries. A history of keloid scarring, for example, suggests that you are likely to develop a keloid after any injury.
Doctors also ask about the nature of the injury that caused a scar. Skin heals differently after a puncture wound or abrasion than it does after a burn or surgical incision, and details about the cause of a scar may help doctors recommend the most effective treatment.