A scar that appears distinctly whiter than the surrounding skin is described medically as a hypopigmented scar. This color difference results from a lack of melanin production within the scar tissue. Repigmentation is often difficult because the cells responsible for color are absent or non-functional. Treatments for restoring color must focus on either stimulating residual pigment cells or transplanting new ones.
Understanding Why Scars Lose Color
The white color of a mature scar is directly related to the deep tissue damage that occurred during the initial injury. Skin color is determined by melanocytes, specialized cells that produce the pigment melanin. When a wound extends deep into the dermis, the normal architecture of the skin is disrupted, and the melanocytes in the injured area are often destroyed or permanently damaged.
During the healing process, the body replaces the damaged tissue with a dense, fibrous collagen matrix. This process, known as fibrosis, does not typically restore the complex cellular layers that include functional melanocytes. The resulting scar tissue lacks the necessary pigment cells to generate color, causing it to appear pale or white.
The visual contrast is often compounded by changes in the scar’s vascularity and the way light reflects off the dense, disorganized collagen fibers. In some mature, hypopigmented scars, melanocytes may still be present but rendered inactive or dysfunctional by the scar environment.
Non-Invasive Topical and Light-Based Strategies
Topical treatments aim to stimulate residual melanocytes. One category includes prostaglandin analogs, such as latanoprost and bimatoprost. These compounds stimulate melanogenesis, the process of melanin production, even in the absence of significant melanocyte proliferation.
Other topical compounds used as adjunct therapies include calcineurin inhibitors, like pimecrolimus and tacrolimus, and certain retinoids, such as tretinoin. These agents are thought to modestly increase the mobility of melanocytes and modulate tyrosinase activity, an enzyme necessary for melanin synthesis.
Targeted light therapy is a common non-surgical method used to activate pigment cells. Narrow-band ultraviolet B (UVB) phototherapy, specifically at a wavelength of 310 to 312 nanometers, is delivered to the hypopigmented area. This radiation stimulates the melanocytes to proliferate and produce melanin.
A more focused application of this technology is the Excimer laser, which delivers light at 308 nanometers directly to the scar. Targeted phototherapy allows for higher, more effective doses of light to be delivered to the white scar while minimizing exposure and potential damage to the surrounding healthy skin.
Clinical and Surgical Repigmentation Treatments
For stubborn white scars that do not respond sufficiently to topical or light-based treatments, fractional ablative laser resurfacing, typically using a Carbon Dioxide (\(CO_2\)) laser, is a common preparatory step. The laser creates thousands of microscopic channels of thermal damage in the scar tissue, serving two primary purposes.
First, the laser energy induces tissue remodeling and stimulates the migration of functional melanocytes from the scar margins into the treated area. Second, the microscopic channels enhance the penetration of topical repigmenting agents. Combining fractional \(CO_2\) laser treatment with topical prostaglandin analogs produces better results than the laser alone.
For scars with complete melanocyte loss, surgical pigment transfer methods physically introduce new pigment cells. One of the oldest techniques is punch grafting, which involves harvesting small, circular pieces of full-thickness skin from a pigmented area. These grafts are then transplanted into corresponding holes created in the scar tissue. While effective, this method can sometimes result in an uneven or “cobblestone” texture at the recipient site.
Autologous Cell Suspension
More advanced surgical options include the use of autologous non-cultured epidermal cell suspension (AECS). In AECS, a small patch of healthy donor skin is processed in a laboratory to create a liquid suspension of melanocytes and keratinocytes. This cellular suspension is then applied onto the laser-prepared scar bed, allowing the pigment cells to spread and establish color over a larger area with minimal donor site morbidity.
Microdermal Grafting
Microdermal grafts are another option, involving the implantation of small strips of skin rich in melanocytes. These strips, often harvested from the scalp, are placed into needle-puncture holes created in the scar.