Keloid and hypertrophic scar

Section: Skin and soft tissue Sub-section: Benign skin and soft tissue] Curriculum: Curriculum, page 52

• See Wounds and wound healing

Definition

• Excessive tissue response to dermal injury, characterised by
  • Local fibroblast proliferation
  • Overproduction of collagen
• Keloid Scar (Greek = Crabs Claw)
  • Fibrous growths that extend beyond the original area of injury, and involves adjacent normal skin
• Hypertrophic Scar
  • Remain confined to boundaries of tissue damage
  • Tend to regress spontaneously over time

Keloid	Hypertrophic scar
Purplish-red Firm, smooth and raised. Uncomfortable and itchy. Can occur years after injury Grow beyond wound edge.	Pink to red Slightly raised or flat Can be uncomfortable and itchy Usually occur within weeks. Limited to confines of wound.

Incidence

• (not precisely known)
• ? 5-16% of Hispanic and African
• M = F, more common younger
• Familial tendency (? AD pattern)

Aetiology

• Risk Factors
  • Location of injury - Back, chest, shoulders, earlobes
  • Trauma
  • Younger 10-30
  • Tension on wound
  • Wound infection
• Genetics (Ethnicity)
  • More common in some ethnic populations
  • African, Asian
  • Family studies show varied modes of inheritance
  • No specific genes yet identified

Pathology

• Pathogenesis incompletely understood
  • Alterations in wound healing
  • ? Multiple local and genetic factors
• Abnormal (increased)
  • Fibroblast proliferation
  • Collagen Synthesis
    • Stretched collagen bundles aligned in same plane as epidermis
    • Normally collagen bundles randomly arrayed and relaxed
• Hypertrophic
  • Can occur anywhere in the body
  • Preventable
• Keloid
  • Genetically predisposed - Inherited metabolic alteration in collagen
  • Atypical fibroblasts
  • More common in darkly pigmented skin,
  • Above clavicles, on trunk, upper limb and face
  • Cannot be prevented
  • Often refractory to medical and surgical intervention

Histology

• Thick, hyalinised collagen bundles
• Consisting of small fibrocytes & separated by bands of immature fibroblasts
• Multiple microvessels that often appear occluded by excess of endothelial cells

Management

Indications and Goals

• Balance of benefit vs risk, and likelihood of recurrence
• Complications of Hypertrophic Scars
  • Pain
  • Pruritus
  • Hyperhidrosis
  • Functional impairment
  • Cosmetic disfigurement
• Goals
  • Relief of symptoms
  • Reduction of the scar volume
  • Functional improvement
  • Cosmetic improvement

Options

• Intralesional steroids
  • Most commonly used management
  • Flattens scar by inhibiting fibroblast proliferation and collagen synthesis
• Intralesional 5-FU (fluorouracil) used as 2nd line
  • Causes fibroblast apoptosis
• Silicone gel sheet
  • Mechanism unknown
• Surgical excision
  • Alone usually followed by recurrence in 45-100%
  • Only indicated if conservative rx fail
  • Best if combined with other approach
• Post-surgical radiation
  • Can be effective
• Colchicine
  • Affects collagen metabolism at three points
    • Inhibits synthesis
    • Stimulates collagenase
    • Affects myofibroblast
• Laser
  • Nd:YAG laser, 585nm pulsed dye laser

Prevention

• Clean and moisturized wound.
• Fix wound with paper tape/steri-strips (to reduce tension)
• Topical steroid if inflammatory tissue develops.
• Make incision along Langers lines.
• Employ techniques to reduce wound tension - subcutaneous/fascial tension reduction sutures.