A keloid is a raised, thickened scar that develops after a skin injury, representing an overgrowth of scar tissue. This dense formation is a form of abnormal wound healing, typically appearing as a firm, rubbery nodule. Keloids are not contagious and cannot be spread from person to person.
Keloids Are Not Contagious
Keloids are a physical manifestation of an internal cellular process that goes awry during tissue repair. They are classified as fibroproliferative disorders, resulting from an excessive and disorganized growth of fibrous tissue. The development of a keloid is purely a localized reaction within the body of the affected individual.
This condition is not caused by any infectious agent, such as a bacteria, virus, or fungus. Since keloids are rooted in the biology of the individual’s wound healing response, they cannot be transmitted through physical contact. Touching a keloid, sharing clothing, or using the same personal items poses no risk of developing the scar.
The scar tissue’s growth is driven by the body’s own cells, specifically fibroblasts, which produce too much collagen. Therefore, keloids do not require isolation or special precautions to prevent their spread to others. They are benign growths and do not represent a systemic disease or a form of cancer.
How Keloids Form
The process begins following an injury to the skin, which can range from a surgical incision, a burn, or a piercing, to minor trauma like acne or a vaccination site. In genetically susceptible individuals, the normal wound healing cascade becomes dysregulated. Instead of stopping once the wound is closed, the reparative process continues unchecked.
This dysregulation results in the excessive production and deposition of collagen, the main structural protein in the skin. Fibroblasts produce collagen at a significantly higher rate than in healthy skin, leading to the formation of a dense, disorganized mass. This aggressive overgrowth is the defining characteristic of a keloid.
Genetic factors play a substantial role in determining who develops these scars, often showing a familial tendency. Keloids are statistically more common in individuals with melanin-rich skin, particularly those of African, Asian, or Hispanic descent.
Defining Keloids Versus Other Scars
Keloids are often confused with hypertrophic scars because both are raised, thick, and firm scars that form after a skin injury. The distinction between the two is based on their growth pattern relative to the original wound boundary. A hypertrophic scar, while raised, remains strictly confined within the borders of the initial injury site.
In contrast, a keloid exhibits aggressive growth, extending horizontally into the surrounding healthy skin beyond the margin of the original wound. This invasive spread is the definitive clinical feature used to diagnose a keloid. The internal structure of a keloid also shows large, haphazardly arranged bundles of collagen.
A key difference lies in their potential for regression. Hypertrophic scars may flatten and soften naturally over several months or years without intervention. Keloids, by comparison, rarely regress spontaneously and often continue to grow slowly over time.
Approaches to Managing Keloids
Managing keloids is often challenging due to their resistance to treatment and high recurrence rates following certain procedures. The most common first-line treatment is the injection of corticosteroids directly into the scar tissue, typically using Triamcinolone acetonide. These injections reduce inflammation and suppress overactive fibroblasts, thereby decreasing collagen synthesis.
Silicone gel sheeting and pressure dressings are also widely used, often as a complementary therapy. These topical methods increase hydration and temperature in the scar, which helps to flatten and soften the tissue over time. These sheets and dressings must be worn continuously for many hours a day over several months for optimal effect.
Another approach is cryotherapy, which involves freezing the keloid tissue with liquid nitrogen to cause cellular destruction and shrink the scar. For larger keloids, surgical removal may be considered, but this is almost always combined with adjuvant therapy, such as corticosteroid injections or radiation. Excision alone is avoided because the trauma of surgery can stimulate the keloid to grow back, often larger than before.