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KELOIDS AND HYPERTROPHIC SCARS

Keloids and hypertrophic scars are abnormalities in the normal wound healing characterized by greater and more sustained extracellular matrix deposition that develops after any insult in the dermis.

It can affect the patient's quality of life, both physically and psychologically.

Hypertrophic scars are raised fibrous tissue scars that remains within the boundaries of the wound. Hypertrophic scars that resulted from surgery or trauma are called linear hypertrophic scars while those from burn injuries or extensive tissue trauma and/or infections are called widespread hypertrophic scars.

Keloids are elevated fibrous scars that extend beyond the borders of the original wound. Major keloids resulted from minor trauma while for those from genetic predisposition with autosomal-predominant features are called minor keloids.

 

 

Definition

  • Patch of fibrous tissue that replaces the normal skin tissue after wounds, trauma, burns, surgical incision, or disease
  • Helps to close open wounds & prevent infection
  • Can be painful, pruritic, & limit mobility

Risk Factors

  • Delay in wound healing due to certain types of trauma eg burns, ear piercing
  • Extent & duration of inflammation
  • Magnitude of mechanical tension acting on the scar
  • Acne, chickenpox, BCG vaccinations, biopsy procedures, & lacerations may cause abnormal scarring
  • Darkly pigmented skin due to the melanocyte-stimulating hormone anomalies
  • Genetic phenotype (familial predisposition) in keloids
  • Black, Hispanic & Asians have increased risk
    • Asian skin has a tendency to develop hyperpigmentation & scar formation after an injury
    • Asians have greater collagen density than Caucasians that manifests a tendency to a more vigorous fibroplastic response during wound healing that results in hypertrophic scarring & prolonged erythema during scar maturation
    • Asian skin also has increased melanin that leads to increased sebum secretion that is characterized by increased proliferation of fibroblast & more vigorous collagen formation & fibroplasia during wound healing
  • Increased prevalence in patients <30 years old (peak 10-20 years)
  • Common in patients w/ elevated hormone levels (eg during puberty or pregnancy)

Pathophysiology

  • Skin wound healing process involves overlapping phases of inflammation, proliferation & maturation or remodelling
    • Hemostasis occurs & an acute inflammatory platelet & white blood cell infiltrate ensue during inflammatory phase
    • Proliferation stage involves fibroplasia, granulation, contraction & epithelialization
    • Remodelling or scar maturation occurs when enough provisional tissue is generated & characterized by disorganized array of collagen & loss of dermal appendages
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