oPatientPlus articles are written by UK doctors and are based on research evidence, UK and European Guidelines. They are designed for health professionals to use, so you may find the language more technical than the condition leaflets.
A keloid scar is one in which there is overgrowth of dense fibrous tissue. This usually develops after the injury has healed. It extends beyond the borders of the original wound. It does not normally regress spontaneously and it will usually recur after excision. This contrasts with hypertrophic scars, which stay within the borders of the original wound.
The term 'chéloïde' was coined by Alibert in 1806, from the Greek 'chele', meaning crab's claw - to describe the lateral growth of tissue into unaffected skin.
- Keloid scars are more common in people with darker skins, especially African-American races.
- The peak age is 10-30 years and keloids are less common at the extremes of age.
- There may be a family history of tendency to develop keloids.
The cause is unknown, although there are various theories, including:
- Dysfunction of the extracellular matrix which controls growth factor activity.
- Abnormalities in collagen turnover.
- An inherited abnormal response to dermal injury.
- An immune reaction to sebum.
- Symptoms: usually cosmetic, although the scar may be tender, painful, itch or produce a burning sensation.
- There is usually a history of trauma that may be accidental, surgical or cosmetic.
- Sites for keloid formation: the most common areas are the sternum, shoulder, earlobe and cheek.
- Burn scars or infected lesions, including acne, are more likely to form keloids.
- The scar has grown beyond the original line of trauma and may be raised and irregular.
- The texture is rubbery.
- It is red in the early stages but becomes brown or pale with age.
- There are no hair follicles or sweat glands within the scar.
- Keloids over a joint can contract and restrict movement.
- Clinical course - the natural history is variable:
- Most lesions grow for weeks-months but growth can continue for years.
- Growth is usually slow but some keloids can enlarge rapidly over months.
- When they stop growing, they remain stable or regress slightly.
- The diagnosis is made clinically; investigations are not required.
- Assess the patient's concerns and the impact of the scar(s) on their life.
- Check if the scar reduces mobility, eg near a joint.
Hypertrophic scars are also red and prominent but do not extend beyond the wound border. Hypertrophic scars usually appear within a month of the injury, grow for several months and then regress; whereas, keloid scars may appear later and continue growing for longer.
Keloid scars are difficult to treat. There are various options. Reviews suggest that combinations of treatments are probably the most effective.
Intralesional steroid injections (with triamcinolone) are a mainstay of treatment and prevention - reviews suggest that it improves the majority of scars.
- Injections are given every 2-6 weeks until improvement.
- Side-effects: pigment changes, telangiectasia and subcutaneous atrophy (which may resolve).
Steroid-impregnated tape applied for 12 hours/day may flatten keloids.
Pressure or occlusive dressings
These are used both for treatment and prevention, with minimal adverse effects, provided they are practical and acceptable to the patient. They must be used for 12-24 hours daily for several weeks or longer.
- Silicone gel - this is applied as topical gel or a gel-impregnated sheet.
- Compression earrings - are used after excision of earlobe keloids and give good rates of recurrence-free healing; they should be worn 24 hours/day.
- Self-adhesive polyurethane scar reduction patches are also suggested.
- Other pressure dressings may be used.
Surgical excision on its own has a very high recurrence rate and the recurring scar may even be larger than the original. Results can be improved by:
- Meticulous surgical technique.
- Additional treatments such as intralesional steroids, occlusive or pressure dressings or radiotherapy.
Radiotherapy is recommended, particularly post-surgery for the treatment of keloid scars. There have been concerns about its safety due to its carcinogenic properties but, providing surrounding tissues are protected, the risk is very low.
Cryotherapy has been used alone and combined with other treatments. Reported results vary:
- Cryotherapy may stop early-stage keloids from growing.
- It may be effective in combination with intralesional steroid.
- Hypopigmentation is a side-effect.
Other possible treatments
- Argon and carbon dioxide laser are probably not effective.
- Pulsed dye lasers and Nd:YAG lasers are reported to give encouraging results, with few adverse effects. However, pulsed dye lasers are less effective on dark skin.
- Laser treatment may reduce the redness of keloids without shrinking them.
- Intralesional interferon alfa-2b has been shown to reduce keloid scars to a greater extent than steroids but is more expensive and causes more discomfort.
- May be beneficial when used alone or in combination with other treatments.
- Possible side-effects are pain, hypopigmentation and tissue sloughing.
- This cytotoxic agent can be given locally as intralesional injections, and improved scars in one small study. Side-effects were hyperpigmentation and dermal atrophy.
- Topical or intralesional retinoids have been used in clinical trials and produced some improvements.
Pharmacological treatment: various agents are being investigated.
For people at high risk of with a history of keloids:
- Avoid body piercing, tattoos and unnecessary incisions such as cosmetic surgery - particularly to skin sites more prone to keloid formation (see under 'Presentation', above).
- Treat acne thoroughly to reduce lesions and potential for scarring.
- If surgery is required, it may be combined with dressings, intralesional steroids or other treatments (see under 'Management', above) to reduce the likelihood or size of keloid scarring. Care with surgical technique is important.
Further reading & references
- Gauglitz GG, Korting HC, Pavicic T, et al; Hypertrophic Scarring and Keloids: Pathomechanisms, Current and Emerging Mol Med. 2010 Oct 5.
- Baron Jean-Louis Alibert (1768-1837)
- Juckett G, Hartman-Adams H; Management of keloids and hypertrophic scars. Am Fam Physician. 2009 Aug 1;80(3):253-60.
- Davidson S, Aziz N, Rashid RM, et al; A primary care perspective on keloids. Medscape J Med. 2009;11(1):18. Epub 2009 Jan 20.
- Al-Attar A, Mess S, Thomassen JM, et al; Keloid pathogenesis and treatment. Plast Reconstr Surg. 2006 Jan;117(1):286-300.
- Leventhal D, Furr M, Reiter D; Treatment of keloids and hypertrophic scars: a meta-analysis and review of the literature. Arch Facial Plast Surg. 2006 Nov-Dec;8(6):362-8.
- Keloids & hypertrophic scars; Keloids & hypertrophic scars, DermNet NZ; Patient information leaflet. Includes illustrations of keloid scars
- O'Brien L, Pandit A; Silicon gel sheeting for preventing and treating hypertrophic and keloid scars. Cochrane Database Syst Rev. 2006 Jan 25;(1):CD003826.
- Ogawa R, Yoshitatsu S, Yoshida K, et al; Is radiation therapy for keloids acceptable? The risk of radiation-induced Plast Reconstr Surg. 2009 Oct;124(4):1196-201.
- Viera MH, Amini S, Valins W, et al; Innovative therapies in the treatment of keloids and hypertrophic scars. J Clin Aesthet Dermatol. 2010 May;3(5):20-6.
Disclaimer: This article is for information only and should not be used for the diagnosis or treatment of medical conditions. EMIS has used all reasonable care in compiling the information but make no warranty as to its accuracy. Consult a doctor or other health care professional for diagnosis and treatment of medical conditions. For details see our conditions.
Dr Naomi Hartree
Dr Laurence Knott