Hypertrophic Scars and Keloids

Snapshot

• A 26-year-old Chinese woman presents to her dermatologist for a persistent growth on her chest. She had previously burned a small portion of her pre-sternal skin while curling her hair 2 years ago. While the burn healed without any problem, she noticed a protuberance where the burn previously was. She reports that this growth seems to be larger than the original burn. On physical exam, she has a 5 cm elliptical firm, pink, and shiny growth. While counselling that this may not go away completely, her dermatologist agrees to start intralesional steroid injections. (Hypertrophic scars)

Introduction

• Clinical definition
  • abnormal and excessive scarring in response to dermal injury, resulting in hypertrophic scars or keloids
• Epidemiology
  • incidence
    • keloid
      • 6-16% of African population
  • demographics
    • most commonly in ages 10-30
  • risk factors
    • keloid
      • ↑ in groups with darker skin
      • patients of African, Hispanic, or Asian descent
      • family history
      • wounds on chest, shoulders, upper arms, earlobes, or cheeks
    • hypertrophic scar
      • wounds on areas of high skin tension
        • shoulders, neck, knees, and ankles
    • both
      • dermal injury caused by burns
      • wounds that take > 3 weeks to heal
• Etiology
  • keloid
    • previous trauma
    • spontaneous
  • hypertrophic scar
    • previous trauma
• Pathogenesis
  • dysregulation of wound healing
    • recall normal wound healing stages are
      • inflammation, proliferation, and remodeling/maturation
  • keloid
    • ↑↑ type I and type III collagen  
      • this is disorganized and extends beyond the original wound
      • abnormalities in melanocyte stimulating hormone may contribute
  • hypertrophic scar
    • ↑ type III collagen
      • this is organized as parallel and confined to the original wound
      • increased activation of myofibroblasts may contribute
• Prognosis
  • keloid
    • recurrence is frequent
    • will not regress over time
  • hypertrophic scar
    • recurrence is rare
• may regress over time

Presentation

• Symptoms 
  • abnormal scarring occurs after trauma or injury
  • often itchy or painful (keloids > hypertrophic scar)
  • keloid 
    • may take months to years to develop
  • hypertrophic scar 
    • usually appears within 1 month
• Physical exam
  • scarring along previous site of wound
  • well-defined, firm, and shiny
  • pink, purple, or hyperpigmented
• irregular borders

Studies

• Biopsy
  • indications
    • only if clinical diagnosis is uncertain
• Histology
  • keloid
    • thick collagen fibers with abundant mucoid matrix
    • disorganized type I and III collagen
  • hypertrophic scar
    • thin collagen fibers with minimal mucoid matrix
    • myofibroblasts
• parallel type III collagen

Differential

• Basal cell carcinoma

Treatment

• Medical
  • intralesional corticosteroid injections
    • indication
      • first-line for treatment that is often used with silicone sheeting
  • silicone sheeting
    • indication
      • first-line for treatment that is often used with intralesional corticosteroid injections
• Operative
  • surgical excision
    • indication
• for scars that are associated with contractures

Complications

• Contractures limiting mobility
  • associated with hypertrophic scars