In short. One stays inside the original wound and often settles; the other grows beyond it. Why the margin decides the plan, and why treating them alike goes wrong.
Key points
- Everything that follows turns on whether the scar has crossed the original wound edge: whether it is likely to settle, whether an operation is a reasonable plan, and what has to accompany an operation if one is done.
- That is why an assessment asks for the operation record or an early photograph.
Two scars can look similar and behave completely differently, and the difference comes down to one question: has the scar stayed inside the edges of the original wound, or has it grown past them? A scar that stays inside is a hypertrophic scar. A scar that crosses the original margins is a keloid. The names matter less than what follows from them: treatment that suits one can make the other worse.
The hypertrophic scar
A hypertrophic scar stays within the boundary of the wound that produced it. It is raised, firm, often red and frequently itchy or tight, and it is most common on sites under tension: the chest, the upper back, the shoulder, the sternum and the jaw. Most hypertrophic scars settle over twelve to eighteen months, flattening and fading to some degree.
The keloid
A keloid does not respect the wound edge. It extends into skin that was never injured, sometimes as a firm, smooth, rounded growth and sometimes with claw-like extensions. It does not settle on its own, and it tends to recur after it is removed, which is the fact that changes everything about how it is managed. It is more common in darker skin and at particular sites, including the earlobe, the chest, the shoulder and the jaw line.
The margin is the finding
Everything that follows turns on whether the scar has crossed the original wound edge: whether it is likely to settle, whether an operation is a reasonable plan, and what has to accompany an operation if one is done. That is why an assessment asks for the operation record or an early photograph.
Why the difference changes the plan
For a hypertrophic scar, time is often the treatment, with the measures used during maturation alongside it and an operation considered once the scar has stopped changing. For a keloid, waiting is not a plan, because it will not settle; and an operation on its own is usually followed by recurrence, so surgery, where it is done at all, is combined with other measures aimed at stopping the scar from rebuilding. A keloid treated as though it were a hypertrophic scar tends to return larger than it started.
What can be said to a patient without examining them is limited, and that is the honest boundary of a page like this one. The distinction is clinical: it is made by looking at the scar, feeling it, asking how it has behaved over time and comparing it with the original wound. It is not something to settle in front of a mirror, and it is not a diagnosis to accept from a description over the telephone.
Have a scar assessed promptly if
- It is growing beyond the edges of the original wound, or still enlarging months after the operation.
- A lump within it is growing, or the scar has started to bleed or ulcerate.
- It is painful or itchy enough to disturb sleep, or it is restricting movement across a joint.
Frequently asked questions
What is the difference between a hypertrophic scar and a keloid?
The wound margin. A hypertrophic scar stays within the edges of the wound that produced it, is most common on sites under tension, and usually settles to some degree over twelve to eighteen months. A keloid grows beyond those edges into skin that was never injured, does not settle on its own, and tends to recur after removal.
Is a keloid dangerous?
It is not a cancer and it is not an infection, and it does not become one. It can itch, hurt, feel tight and be conspicuous, and a keloid over a joint can restrict movement. The reason it matters is not danger but behaviour: it does not settle, and it returns after it is removed, which changes what can honestly be offered.
Why does a keloid come back after it is removed?
Because the operation creates a new wound in skin that has already shown it heals by overgrowing scar tissue, and that wound is closed under the same tendency. This is why an operation for a keloid is considered together with other measures aimed at preventing the scar from rebuilding, rather than on its own.
Risks & Limitations
- A scar is permanent. Maturation changes its colour, height and firmness over twelve to eighteen months, not its existence.
- A raised scar is usually uncomfortable rather than dangerous, which is why the small number of findings that are dangerous are named individually.
- Maturation is slow, and a scar often looks worse at six weeks than it will at six months; judging it early means judging a moving target.
- Treatment can improve a scar but cannot remove it, and a further operation trades one scar for another arrangement rather than undoing the first.
- A keloid grows beyond the original wound, does not settle on its own, and tends to recur after it is removed.
When to Seek Care
- A scar growing beyond the edges of the original wound, or a lump within it that is enlarging — have it assessed within days.
- Redness with heat, swelling or discharge in the scar, or a fever — seek care the same day.
- A wound that has opened, or a gap appearing along the scar — seek care the same day.
- A scar tightening across a joint, or pulling on an eyelid or a lip — prompt assessment.
- A scar that has started to bleed or ulcerate — urgent assessment.
References & Further Reading
- American Society of Plastic Surgeons (ASPS) — guidance on scar revision and surgical wound care
- National Institute for Health and Care Excellence (NICE, UK) — guidance on surgical scars and wound management
- Cochrane Library — systematic reviews of scar management
- American Academy of Dermatology (AAD) — guidance on keloids and hypertrophic scars
- Chinese Medical Association Plastic Surgery Branch — clinical guidance
This page is patient education, not medical advice, and it does not cite individual studies. Discuss your own case with a qualified clinician. To arrange an assessment at Chongqing West District Hospital, see Contact & Consultation.