Keloids / Hypertrophic Scars

Content of This Page

1- Definition & Distinction

2-Aetiology & Risk Factors

3-Pathophysiology

4- Clinical Presentation

5- Histological Differences

6- Differential Diagnosis

7- Treatment Strategies

8- Prevention & Patient Education

9- Core Summary Points

Definition & Distinction

  • Hypertrophic scars are raised, red scars that stay within the boundaries of the original wound.

  • Keloids are raised, firm scars that grow beyond the original wound margins and do not regress spontaneously.

FeatureHypertrophic ScarKeloid
DefinitionThickened scar that remains within the boundary of original woundScar that extends beyond the original wound margins
Growth patternStabilizes or regresses over timeMay continue growing for months/years
HistologyCollagen in parallel bundlesThick, haphazard collagen bundles (type I & III)

Aetiology & Risk Factors

  • Skin trauma: surgery, burns, piercings, tattoos, acne

  • Genetic predisposition: more common in individuals of African, Asian, or Hispanic descent

  • Younger age: more common in ages 10–30

  • High-tension areas: chest, shoulders, upper back, earlobes

Pathophysiology

  • Abnormal wound healing response involving:

    • ↑ fibroblast activity

    • Excess collagen synthesis (mainly Type I and III)

    • ↓ collagen degradation (due to low collagenase)

    • ↑ growth factors (e.g. TGF-β)

  • Keloids: have a persistent proliferative and inflammatory response

Clinical Presentation

FeatureHypertrophic ScarKeloid
LocationAt wound siteExtends beyond
OnsetWeeks after injuryMonths after injury
SymptomsMay be itchy/painfulOften painful, pruritic
ProgressionMay regress over timeOften progressive

Histological Differences

  • Hypertrophic scar:

    • Collagen arranged in parallel bundles

    • More confined vascularity

  • Keloid:

    • Thick, haphazard collagen bundles

    • Prominent blood vessels, chronic inflammation

© image from Wikimedia Commons

Differential Diagnosis

  • Dermatofibroma

  • Dermatofibrosarcoma protuberans (DFSP)

  • Hypertrophic lupus lesions

  • Scleroderma plaques

  • Biopsy may be required if diagnosis is uncertain or malignancy is suspected.

Treatment Strategies

First-line:

  • Intralesional corticosteroids (e.g. triamcinolone)

    • Reduces inflammation and collagen production

– Adjuncts:

  • Silicone gel sheeting or dressings

  • Compression therapy (earrings, pressure garments)

  • Topical imiquimod (for post-excision keloid prevention)

– Advanced Options:

  • 5-fluorouracil (5-FU) or bleomycin injections

  • Pulsed dye laser therapy

  • Cryotherapy (esp. for smaller keloids)

– Surgical Excision:

  • Only in combination with steroids, radiotherapy, or silicone to prevent recurrence

Prevention & Patient Education

  • Avoid unnecessary cosmetic procedures in high-risk patients

  • Use sterile techniques in piercings or surgeries

  • Apply silicone gel sheets after wounds or surgery

  • Educate patients on early treatment signs of raised scarring

Core Summary Points

  • Keloid = outgrows wound boundary, recurs frequently

  •  Hypertrophic scar = raised but remains within wound, may regress

  •  Corticosteroids are the first-line treatment

  •  Always use multimodal therapy for resistant cases

  •  Prevention is better than cure—especially in high-risk ethnic groups

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