Topical Scarring & Burns

Scars (or fibrosis) are often the result of aberrant tissue repair processes. Fibrosis occurs when normal tissue repair pathways become dysregulated, causing excessive collagen and fibronectin deposition in wounds and affected organs that ultimately impairs their physiological function. More than 100 million patients develop scars each year as a result of 55 million elective operations and 25 million operations after trauma in the developed world alone Excessive scars form as a result of aberrations of physiologic wound healing and may develop following any insult to the deep dermis, including burn injury, lacerations, abrasions, surgery, piercings and vaccinations. By causing pruritus, pain and contractures, excessive scarring can dramatically affect a patient’s quality of life, both physically and psychologically.

Hypertrophic & Keloid Scars

Excessive scarring was first described in the Smith papyrus about 1700 BC. Many years later Mancini (in 1962) and Peacock (in 1970) differentiated excessive scarring into hypertrophic and keloid scar formation. Per their definition, both scar types rise above skin level, but while hypertrophic scars do not extend beyond the initial site of injury, keloids typically project beyond the original wound margins.

Hypertrophic scars and keloids are ﬁbroproliferative disorders occurring, often unpredictably, as a result of trauma and inﬂammation that compromise cosmesis and function and, in the case of keloids, commonly recur following surgical attempts for improvement. They are characterized by chronic local inflammation and excessive deposition of extracellular matrix components, especially collagen and fibronectin, in the dermis and subcutaneous tissue,that extend, in some cases, beyond the original site of injury.

Hypertrophic scar (HSc) represents an undesirable endpoint of wound healing, where abnormal extracellular matrix (ECM) accumulation and cellular activity result in thick, unsightly, and symptomatic scar tissue. HSc is made of nodules of disorganized collagen ﬁbrils surrounded by parallel sheets of ﬁbrils. Keloids are benign dermal ﬁbrotic tumors that grow beyond the boundaries of the initial wound. Keloids contain large, thick collagen ﬁbers composed of numerous ﬁbrils closely packed together.

Burns

Burns and burn-related injuries are still a major overwhelming public health issue. Every day, more than 30,000 people suffer new burns worldwide, severe enough to require medical attention, equating to an estimated 11 million new burns each year globally.

Cutaneous scarring remains the pathognomonic feature following burns to the skin and characteristically underlies post-burn physical and psychosocial morbidity. The most common cicatrix formed following a burn is the hypertrophic scar, the prevalence of which has been reported as being as high as 70%. Patients with these massive burns have extensive scarring and contractures, itch, and pain. They are dissatisfied with their appearance and experience restricted movement, itch, and loss of function for many years. The greatest unmet challenges in burn rehabilitation relate to decreased quality of life and delayed reintegration into society resulting from post-burn scar.

Following cutaneous injury, the defect is healed through creation of a scar, with linear collagen deposition lacking the flexibility of uninjured skin. Although the desired result for any healing wound is scarless healing, the best result is usually a flat, pliable scar with slight discoloration. Deposition of excess collagen results in a pathologic scar that is thick, nonpliable, itchy, and painful. One of two types of pathologic scars arises from the burn wound – a hypertrophic scar or a keloid. The mechanisms underlying the development of either scar differ, and each scar type is managed differently. Hypertrophic scars occur within the confines of the original wound, mature within ~2 years, and do not return following excision. Keloids grow beyond the edge of the initial wound with persistence of the proliferative phase for an extended time, with a recurrence rate ranging from 70% to 90% following excision. A small number of burn patients develop keloids.

Post-Operative Scars

Each year approximately 234 million major surgical procedures are performed worldwide resulting in varying degrees of scar as a visible endpoint of wound healing. These scars can range from indistinguishable, fine lines to painful, disfiguring hypertrophic and keloid scars. While scar formation is affected by a number of patient-specific variables, efforts to minimize scar formation have been motivated by the unpredictability and potential for abnormal scarring. Scar formation can lead to dissatisfaction among patients, including those undergoing elective surgery like abdominoplasties. The formation of scars following surgery is therefore of particular interest to plastic surgeons.

Atrophic Acne Scars

Acne is a common condition that affects up to 80 percent of the adolescent population to some degree or another. It is caused and characterized by multiple factors including Propionibacterium acnes activity, increased sebum production, androgenic stimulation, follicular hyper cornification, lymphocyte, macrophage and neutrophil inflammatory response, and cytokine activation. Inflammatory acne lesions can result in permanent scars. Scarring occurs early in acne and may affect some 95 percent of patients with this disease, relating to both its severity and delay before treatment. Acne scars can be classified into three different types: atrophic, hypertrophic, or keloidal. Atrophic acne scars are the most common type. The pathogenesis of atrophic acne scarring is most likely related to inflammatory mediators and enzymatic degradation of collagen fibers and subcutaneous fat. The most basic and practical system divides atrophic acne scars into three main types: ice pick, rolling, and boxcar scars. A number of treatments are available to reduce the appearance of scars. Treatment of acne scars must be individually directed for each patient depending on the types of scars present.