A keloid refers to a chronic, persistent scar-like plaque or nodule that extends beyond the site of an original skin injury due to excessive deposition of collagen in the dermis by fibroblasts. A hypertrophic scar is confined to the site of the original wound and can self-resolve. Keloids can be very itchy and painful. Patients also seek treatment for the psychosocial impact they can have related to the appearance. Simple excision is rarely effective, as they almost always recur.

Keloids are more common, and tend to grow larger, in people with dark skin and Asians. They typically occur between ages 20-30 years in both women and men. The elderly and young children are rarely affected. Sometimes, keloids occur in families.

It’s unknown why some individuals tend to develop keloids and others do not. The pro-fibrotic cytokine, transforming growth factor beta (TGF-beta) plays a key role. Keloids tend to occur after trauma, but not always.

Common triggers of keloids:

• surgical incision
• cut/laceration
• burn
• ear piercing
• tattoo
• injection
• vaccination
• acne pustule
• abscess
• insect bite

Clinical features

Keloids are well-demarcated, firm, scar-like, irregularly-shaped, plaques or nodules, usually arising in a site of previous skin injury. The overlying epidermis is shiny and thin. Lesions often progress from pink to red to purple with surrounding erythema, and telangiectasias and can be itchy, tender or painful.

A patient will often have more than one lesion. They range in size from a few millimetres to more than 10 centimetres. Keloids can be linear, often bulbous at the ends with central regression, or spherical. They are distinguished from a hypertrophic scar by extending beyond the margins of the original injury, sometimes with claw-like extensions.

Keloids can occur anywhere, but favour sites with increased skin tension such as:

• sternum (most common)
• ears
• neck
• mandible
• shoulders
• arms

The main differential diagnosis to consider is a hypertrophic scar. For atypical lesions, without preceeding injury, consider keloidal forms of morphea, and scleroderma, as well as dermatofibroma, or rarely, dermatofibrosarcoma protuberans. Complications include hyperpigmentation, ulceration and draining sinus tracts.

Investigations

Keloids are mainly a clinical diagnosis. If the history or clinical findings are not classic for a keloid, or if there are any doubts, consider taking a biopsy of the lesion for histopathology to rule out a malignancy. Under the microscope, a keloid shows large thick, hyalinized collagen bundles in the dermis, pushing other structures aside.

Treatment

Treating keloids is challenging, as they have a poor response to interventions, and — unlike hypertrophic scars — they rarely self-resolve. Many options are available and there is no single best treatment. It is difficult to predict which one a patient may respond to and combinations are often more helpful than any one therapy. Key components include patient education and prevention.

Strategies for prevention:

• careful suturing technique during cutaneous closure
  • minimize epidermal tension and inflammation
  • wound closure should parallel skin lines
• consider avoiding cosmetic procedures in those with a history of keloids
• be cautious when performing procedures in high risk areas for keloids

Treatment options for keloids

Compression therapy

• thins keloids, perhaps by inducing local tissue hypoxia

Occlusive dressings

• silicone gel sheets
  • anti-keloidal effect, perhaps due to hydration and occlusion — decreases capillary activity resulting in less collagen deposition
  • apply daily and overnight
  • especially helpful at reducing itch

Topical therapies

• topical corticosteroids
• corticosteroid-impregnated tape
• imiquimod 5% cream
  • excision followed by application of imiquimod nightly for 8 weeks, 6-month follow-up with no recurrences
• Topical retinoids
• Topical tacrolimus

Intralesional therapies

• intralesional corticosteroids — mainstay of keloid therapy
  • triamcinolone acetonide, 10-40 mg/ml
    • consider using a lower concentration as the lesion improves
    • inject into keloid with a 25-30 gauge needle every 4-6 weeks
    • caution regarding risk of atrophy
    • may recur and require further treatment
    • hyperpigmentation seldom resolves
• intralesional interferon
  • Interferon-alfa-2b
    • reduces occurrences post-op (day of procedure and repeated 1 week later)
• intralesional 5-fluorouracil
  • weekly injections for 2-3 months, with majority showing 50% reduction in height
• intralesional bleomycin
  • weekly for 1 month
• intralesional verapamil

Cryosurgery

• liquid nitrogen, freezing tissue causes cell damage and tissue anoxia
• 1-2 freeze thaw cycles from 10-30 seconds monthly
• may be more effective if combined with intralesional corticosteroids

Radiation therapy

• can be effective, but there is a very small risk of malignancy in the treated area
• typically applied to excision scar and 1-2 cm of surrounding skin within 1-3 days after surgery

Laser therapy

• destructive lasers
  • CO₂ laser — often recur
• vascular lasers
  • 585 nm pulsed dye laser
    • reduces itch and redness, scar height

Excision

• recurrence is extremely common
  • risk of larger keloids
• immediately after excision, initiation of therapy with other modalities can be tried to prevent recurrence.