A scar is the biological replacement tissue your body uses to patch a wound after a deep injury. When a wound extends beyond the top layer of skin, the body shifts from regeneration to rapid repair, resulting in a fibrous patch rather than a perfect copy of the original tissue. This emergency repair often appears red or purple at first, but many mature scars eventually settle into a noticeably pale or white color compared to the surrounding skin.
How Scar Tissue is Formed
Scar formation is the final stage of wound healing, beginning when the body needs to quickly restore the structural integrity of the skin. Specialized cells called fibroblasts migrate into the wound site and become activated, transforming into myofibroblasts. These cells are responsible for the massive synthesis and deposition of the extracellular matrix that forms the scar tissue. The primary component of this new matrix is collagen, specifically Type I collagen, which is rapidly produced to close the defect.
In normal, uninjured skin, collagen fibers are arranged in a complex, woven basket-weave pattern that allows for flexibility and elasticity. Scar tissue, by contrast, features collagen bundles that are packed densely and aligned in a more parallel, linear fashion along the lines of tension. This fast, organized alignment provides strength but results in tissue that is structurally inferior to the original skin.
Why Scar Tissue Lacks Pigment
The most direct reason for a scar’s white appearance is hypopigmentation, which means the tissue lacks the normal amount of color. Skin color is determined by melanin, a pigment produced by specialized cells called melanocytes. These melanocytes reside in the basal layer of the epidermis, the top layer of skin.
When an injury is deep enough to result in a scar, it often destroys or significantly damages the melanocytes in the affected area. During the rapid process of wound repair, the body prioritizes closing the wound over perfectly regenerating all specialized cell types, including melanocytes. This absence of melanin also means the scar cannot tan or darken when exposed to ultraviolet (UV) light, making the difference in color more pronounced during summer months. The lack of this natural protection also puts the scar tissue at a higher risk for UV-related damage.
Structural Differences in Mature Scars
The final white color of a mature scar is not solely due to the lack of pigment but is also influenced by structural changes that occur during the maturation phase. Initially, a healing scar often appears red or pink because the body increases blood flow to the area, resulting in high vascularity necessary to deliver nutrients for repair. As the scar matures and the healing process concludes, the number of blood vessels decreases significantly, a process known as vascular regression.
Furthermore, the dense, highly organized bundles of Type I collagen that form the bulk of the scar tissue reflect light differently than the surrounding skin. This difference in light reflection, combined with the decreased vascularity and the lack of melanin, contributes to the final, pale or translucent white appearance of the mature scar.