Patch of fibrous tissue that replaces the normal skin tissue after wounds, trauma, burns, surgical incision or disease
Helps to close open wounds and prevent infection
Can be painful, pruritic and limit mobility
Risk Factors
Delay in wound healing due to certain types of trauma (eg burns, ear piercing)
Extent and duration of inflammation
Magnitude of mechanical tension acting on the scar
Acne, chickenpox, Bacille Calmette-Guérin (BCG) vaccinations, biopsy procedures and lacerations may cause abnormal scarring
Darkly pigmented skin due to the melanocyte-stimulating hormone anomalies
Genetic phenotype (familial predisposition) in keloids
Black, Hispanic and Asians have increased risk
Asian skin has a tendency to develop hyperpigmentation and 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 and 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 and more vigorous collagen formation and fibroplasia during wound healing
Increased prevalence in patients <30 years old (peak 10-20 years)
Common in patients with elevated hormone levels (eg during puberty or pregnancy)
Pathophysiology
Skin wound healing process involves overlapping phases of inflammation, proliferation, and maturation or remodeling
In the inflammatory phase, hemostasis occurs, followed by an acute inflammatory platelet and white blood cell infiltration
Proliferation stage involves fibroplasia, granulation, contraction and epithelialization
Remodeling or scar maturation occurs when enough provisional tissue is generated and characterized by disorganized array of collagen and loss of dermal appendages
