A keloid is a type of scar tissue that grows excessively, forming a raised, often firm or rubbery growth on the skin. This abnormal healing response results from the body overproducing collagen following an injury to the skin. Unlike typical scars that flatten and fade over time, a keloid continues to expand and extend beyond the original boundaries of the wound.
Understanding Keloids vs. Hypertrophic Scars
The public often uses the terms keloid and hypertrophic scar interchangeably, but they are distinct conditions with different prognoses. A hypertrophic scar is a thickened, raised scar that remains confined to the area of the initial injury. These scars typically appear within weeks or months and may soften and flatten over 12 to 24 months.
Keloids, in contrast, are characterized by their ability to spread horizontally, invading the surrounding healthy skin far past the original wound margins. They tend to emerge in a delayed fashion, sometimes taking three months to a year or more to become noticeable after the inciting event. This difference in growth pattern is a defining feature that distinguishes the two types of scarring.
The underlying structure of the tissue also shows a clear distinction under microscopic examination. Hypertrophic scars contain collagen fibers that are generally organized in a parallel pattern relative to the skin’s surface. Keloids, however, are histologically defined by thick, disorganized bundles of collagen that appear glassy and hyalinized, often referred to as keloidal collagen. Keloid tissue also features a significantly higher concentration of collagen production, sometimes up to 20 times the normal amount seen in healthy skin.
The Likelihood of Spontaneous Regression
Keloids rarely, if ever, resolve completely without medical intervention. The abnormal healing process involves an unchecked, persistent production of fibrous tissue that does not naturally cease or reverse. Instead of fading, a keloid may continue to grow slowly for months or even years.
While some keloids may become slightly softer or less symptomatic over many years, they do not disappear entirely. This lack of spontaneous resolution contrasts sharply with hypertrophic scars, which frequently flatten and become less noticeable over time without treatment.
If a keloid is left untreated, it may eventually stop growing, but the raised, discolored mass of tissue remains permanently. In a small fraction of cases, some patient-reported softening and flattening of the lesion has been observed, but the scar tissue itself remains visible and palpable. For this reason, medical treatment is usually necessary to reduce the size or improve the appearance of the lesion.
Why Keloids Form and Who is Susceptible
Keloids are a result of a dysregulated wound healing process, specifically an overactive response by fibroblasts, the cells responsible for synthesizing collagen and the extracellular matrix. After a skin injury, the fibroblastic phase of healing fails to shut down, leading to the excessive deposition of collagen that forms the scar. This mechanism results in a collagen synthesis rate that is significantly higher than in normal wound healing.
A strong genetic component predisposes certain individuals to keloid formation, with a family history being a major risk factor. Individuals with darker skin pigmentation, including those of African, Asian, and Hispanic descent, have a markedly higher prevalence. The risk is estimated to be up to 15 times greater in some populations compared to those with lighter skin tones.
Keloids are most commonly seen in people between 10 and 30 years old. They can be triggered by any form of skin trauma, ranging from surgical incisions to minor injuries like acne, insect bites, or burns. Certain anatomical areas, such as the earlobes, shoulders, upper back, and chest, are recognized as sites where keloid formation is more likely due to higher skin tension.
Medical Approaches for Keloid Management
Since keloids do not regress naturally, medical intervention is necessary to manage their growth and appearance. First-line treatments often involve intralesional corticosteroids, such as triamcinolone acetonide, injected directly into the scar tissue. These injections reduce inflammation and suppress overactive collagen synthesis, with response rates ranging from 50% to 100%.
Silicone sheeting and pressure therapy are utilized as non-invasive, first-line approaches. Continuous pressure, often applied by specialized garments or earrings, helps flatten the scar and minimize recurrence, particularly when used immediately after an injury or procedure. These methods work by reducing tension and blood flow to the area, thereby inhibiting fibroblast activity.
For more established or resistant keloids, other treatments are employed, including cryotherapy (freezing the scar tissue) and laser therapy. Cryotherapy is usually reserved for smaller lesions, while pulsed-dye lasers reduce the redness and size of the scar. Intralesional injections of other agents, such as 5-fluorouracil or interferon, may be used as an alternative or in combination with corticosteroids.
Surgical excision of a keloid, while possible, carries a high risk of recurrence, sometimes as high as 45% to 100% when performed alone. Surgery is almost always combined with an adjunctive therapy to prevent the new scar from reforming. Postoperative treatments often include a course of corticosteroid injections, radiation therapy, or the topical application of Imiquimod cream to suppress the healing response.