Scar tissue generally does not spread, but specific types of abnormal scarring can actively grow and expand beyond the original injury site. The body initiates a healing process after a deep skin injury, replacing damaged tissue with fibrous connective tissue. This essential repair mechanism sometimes results in overgrowth when the tight regulation of cellular activity is lost. Understanding the difference between a typical, mature scar and one that continues to grow is key to addressing concerns about scar tissue spreading.
The Limits of Normal Scar Formation
Normal skin repair is a tightly controlled biological process involving three main phases: inflammation, proliferation, and remodeling. During the proliferative stage, specialized cells called fibroblasts migrate to the injury site. They produce large amounts of collagen, a tough structural protein, to create a provisional matrix, which is gradually replaced by a scar that is initially red and raised.
The final stage, remodeling, can last for a year or more as collagen fibers are broken down and re-laid to increase the scar’s strength. Once the repair work is complete, fibroblasts undergo programmed death (apoptosis). This cessation of collagen production ensures that the resulting mature scar does not continue to grow or migrate beyond the precise boundaries of the original wound. A fully healed, flat, and pale scar represents this controlled endpoint of dermal repair.
Pathological Scarring: When Tissue Overgrows
When the wound healing process becomes dysregulated, it leads to pathological scarring characterized by excessive and prolonged tissue production. This overgrowth takes two primary forms: hypertrophic scars and keloid scars. The key difference between them lies in their behavior relative to the original injury margins.
Hypertrophic scars are characterized by an overabundance of collagen, causing the scar to be raised, red, and firm, but they strictly remain within the confines of the initial wound site. They typically develop within weeks of the injury and may cause itching or pain. However, they often show a tendency to improve and flatten over time, even without aggressive treatment.
In contrast, keloid scars are the true example of scar tissue that spreads beyond its original borders, invading the surrounding healthy skin. Keloids result from an aggressive, sustained overproduction of collagen that does not stop once the wound is closed, and they rarely regress spontaneously. They can appear months after the initial injury and continue to enlarge for years, often presenting as firm, rubbery, or lumpy growths that may be intensely itchy or painful.
Biological and External Risk Factors
The development of excessive scarring is influenced by a combination of internal biological and external environmental factors. Genetic predisposition is a significant internal factor, particularly for keloids, with individuals of African, Asian, and Hispanic descent being statistically more susceptible. Darker skin types are generally more prone to this type of abnormal healing.
Age is another biological determinant, with individuals typically between 10 and 30 years old showing the highest risk. External factors often relate to the nature and location of the wound. Wounds in areas of high skin tension are more likely to develop pathological scars due to constant mechanical stress. Delayed wound healing, often caused by infection or prolonged inflammation, also significantly increases the risk of excessive collagen deposition.
Strategies for Managing Excessive Scarring
Managing excessive scarring focuses on both prevention and reduction once the scar has formed. Non-invasive techniques are often the first line of approach, applied once the wound has fully closed. Silicone sheets and gels are considered the primary treatment, working by increasing skin hydration and regulating cellular activity to suppress collagen overproduction.
Pressure therapy, which involves wearing custom-made pressure garments, is especially effective for preventing and treating large, widespread scars, such as those resulting from severe burns. This mechanical compression is thought to reduce blood flow and inhibit collagen synthesis within the scar tissue.
Medical Interventions
For more stubborn or established pathological scars, medical interventions may be necessary. These include intralesional corticosteroid injections, which work by reducing inflammation and breaking down collagen. Surgical revision is also an option, but it is often combined with adjuvant therapies like steroid injections due to the high risk of recurrence, especially with keloids.