Scars

摘要

If the papillary layer of the stratum corneum (outer layer of the skin) is damaged or destroyed, a scar will form. When a wound heals the repaired tissue is not an exact replica: it is fibrous in nature and devoid of blood vessels and skin appendages such as hair and sebaceous glands. Scar tissue is a natural part of the healing process. Over time, the initial livid colour of a scar will fade and become less prominent, although some scars change and develop into unsightly hypertrophic or keloid scars. Nearly all atypical scars occur in traumatic or surgical wounds; possible causes include reaction to a foreign body, anoxia, prolonged inflammatory response and infection.Hypertrophic scars are raised above the surrounding skin but do not extend laterally. It is thought that apoptosis of inflammatory cells and fibroblasts contribute to their development. Keloids extend beyond the borders of the original scar and can continue to grow. They respond poorly to surgical revision and so may be more painful.