A keloid is a raised, firm scar that grows beyond the edges of the original wound. That overgrowth is the single most important feature that separates a keloid from a normal scar or other types of raised scars. If a scar stays within the boundaries of your injury, it’s probably not a keloid. If it has spread outward into skin that was never damaged, that’s the hallmark sign.
What a Keloid Looks and Feels Like
Keloids are dense, rubbery or firm lumps of scar tissue that rise above the surrounding skin. They can be smooth and shiny on the surface, and their color varies depending on your skin tone: pink, red, or purple on lighter skin, and darker brown or hyperpigmented on deeper skin tones. Over time, many keloids flatten slightly but remain noticeably thicker and harder than normal skin.
The size of a keloid depends on the original injury and how long it keeps growing. Some are small, rounded bumps (common on earlobes after piercings), while others form large, spreading masses across the chest or shoulders. Unlike a typical scar that stabilizes after a few months, a keloid can continue expanding for years. There is no predictable stopping point.
Itching, Pain, and Other Sensations
Keloids aren’t just a cosmetic issue. Roughly 50 to 90 percent of people with keloids experience pain, itching, or both. The itching tends to be worst around the edges of the keloid rather than the center, because nerve fibers are packed more densely at the border where the scar is actively pushing into healthy skin. The stiff scar tissue pulls on surrounding nerves, creating a chronic low-level irritation that can feel like tightness, tenderness, or a prickling sensation.
These sensory symptoms are tied to ongoing inflammatory activity inside the keloid. Immune cells release compounds that directly stimulate nerve fibers, which is why a keloid can feel uncomfortable even years after the original wound healed. If your scar itches persistently, feels tender to the touch, or causes occasional sharp twinges, those are signs consistent with keloid behavior.
How Keloids Differ From Hypertrophic Scars
The scar most commonly confused with a keloid is a hypertrophic scar. Both are raised, both can be red or discolored, and both form after skin trauma. But they behave differently in three important ways.
- Boundaries: A hypertrophic scar stays within the borders of the original wound. A keloid extends past those borders into undamaged skin.
- Timing: Hypertrophic scars typically develop within weeks of an injury and often improve on their own over months to a year or two. Keloids can appear months or even years after the triggering event and rarely resolve without treatment.
- Response to treatment: Hypertrophic scars are more likely to flatten and fade with standard scar treatments. Keloids tend to persist and are significantly more resistant to treatment. They also have a high rate of recurrence after removal.
If your raised scar appeared quickly after surgery or an injury, has stayed the same size as the wound, and seems to be slowly softening, it’s more likely hypertrophic. If it showed up later, keeps creeping outward, and hasn’t improved, keloid is the stronger possibility.
When and Where Keloids Tend to Form
Keloids most commonly develop on the chest, upper back, shoulders, and earlobes. These are areas where skin is under relatively high tension during normal movement, which appears to drive the excess collagen production behind keloid growth. Piercings (especially ear and cartilage piercings), surgical incisions, acne scars, burns, and even minor scratches can all trigger a keloid in someone who is prone to them.
A keloid can form anywhere skin has been injured, but some people notice their first one after a routine event like getting ears pierced or having a mole removed. The delay between injury and keloid formation varies widely. Some develop within a few months. Others don’t appear for a year or more, which can make it hard to connect the scar to its original cause.
Who Is More Likely to Get Keloids
Keloids are strongly influenced by genetics. If your parents or siblings develop keloids, your risk is substantially higher. Researchers have identified multiple regions of the human genome associated with keloid formation, and the fact that these regions are on different chromosomes in different families underscores how complex the genetic component is.
Ethnicity plays a significant role. People of Black, Hispanic, and Asian descent develop keloids at much higher rates than white individuals. Within Asian populations, studies have found variation as well, with some ethnic groups affected more than others. People with blood type A also appear to have a slightly elevated risk, though the connection isn’t fully understood. If you have darker skin and a family history of thick or raised scars, any new scar that keeps growing should raise suspicion for a keloid.
How Keloids Are Diagnosed
In most cases, a doctor can diagnose a keloid simply by looking at it. The combination of a raised scar that has grown beyond the wound margins, along with your history and symptoms, is usually enough. No blood tests or imaging are needed.
Occasionally, a small skin biopsy may be taken, not to confirm the keloid itself, but to rule out other conditions like certain skin cancers that can sometimes mimic the appearance of a raised, firm growth. This is more likely if the scar appeared without an obvious injury or if it looks unusual in color or shape.
What’s Happening Under the Skin
Normal wound healing involves your body laying down collagen to close a wound, then gradually remodeling that collagen into a flat, stable scar. In a keloid, that process goes off track. The cells responsible for producing collagen (called fibroblasts) are present in higher numbers and don’t stop working when they should. They keep building collagen and pushing it outward into surrounding tissue.
Part of what drives this is a feedback loop between the scar tissue and the cells inside it. As the scar stiffens, the fibroblasts sense that rigidity and respond by producing even more collagen, migrating outward, and multiplying. This is why keloids are self-perpetuating: the thicker and stiffer the scar gets, the more aggressively the cells inside it behave. It also helps explain why keloids are so difficult to treat and why they frequently return after surgical removal, since the underlying cellular behavior hasn’t changed.