Scars: Types, Causes, and Treatment

A scar is the fibrous tissue that replaces normal skin following cutaneous injury or ulceration, marking the final stage of the physiological wound healing process.Clinically, it presents as an elevated or depressed area with alterations in skin texture, pigmentation, nerve supply,vascularity, and biomechanical properties,reflecting a disruption of normal skinstructure and function.

Histologically, scar tissue shows a thickened epidermis with a flattened dermo-epidermal junction and an abnormal dermal matrix composed of small, densely packed, parallel collagen fibers-primarily type III collagen and fibronectin-unlike the basket-weave pattern of normal dermis.

Elastic fibers are fragmented and abnormally organized, and epidermal adnexal structures such as hair follicles and sebaceous glands are typically absent, contributing to the scar’s altered appearance and function. (1)

Following injury, the wound healing process initiates promptly, resulting in the (partial) restoration of the damaged tissue. This process progresses through four dynamic, overlapping, and interrelated phases.

Based on morphological alterations observed in the wound tissue over time, these phases are classified as the hemostasis phase (marked by capillary damage), the inflammatory phase, the proliferative phase (characterized by the formation of granulation tissue and reepithelialization), and the remodeling phase, which encompasses tissue maturation and scar formation. (2)

Atrophic Scars: Atrophic scars are characterized by localized cutaneous atrophy, involving a reduction in cutaneous cells in the epidermis. Clinically, they present as skin depressions and are most commonly observed following acne, cyst, varicella infection, burn, injury or latrogenic surgery. (3)

Hypertrophic Scars: Hypertrophic scars are firm, raised scars confined to the original wound borders, typically forming within weeks of injury. They are characterized by excessive collagen deposition arranged in a wavy, regular pattern. (4)

Keloid Scars: These are raised scars that extend beyond the wound margins with no distinct patterns of collagen, and do not regress. Genetic predisposition plays a significant role in their development. (4)

Contracture Scars: Contracture scars are pathological scars caused by excessive wound contraction, often following burns, trauma, or infections. They commonly affect mobile areas like the neck, joints, hands, and face, leading to functional impairment from restricted skin movement. (5)

Abnormal scarring, such as hypertrophic scars and keloids, results from dysregulated wound healing with fibroblast overactivity, higher collagen deposition, and extended inflammation. These scars can lead to chronic pain, pruritus, and contractures that interfere with daily activity and affect emotional well-being.