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A Practical Approach to Classification and Treatment of Scars

Tiffany Kwok, MD and Jaggi Rao, MD, FRCPC

Division of Dermatology and Cutaneous Sciences, University of Alberta, Edmonton, AB

Introduction

Scarring, whether from planned surgical procedures or a sequela of inflammatory conditions such as acne, striae, burns or trauma, is often associated with considerable emotional impact. As a result, patients often seek the advice of physicians regarding scar revision. This paper focuses on a comprehensive and practical approach to classifying and managing scars in terms of colour and texture, and discusses topical treatments accessible to family physicians in more detail.

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Scar Formation

  • Scars are part of the normal healing process after cutaneous injury. The process is part of the remodeling phase of wound repair, following the phases of hemostasis and inflammation.
    • The wound repair phase involves re-epithelialization, neocollagenesis, neovascularization, and pigment deposition.
  • Scar formation can take up to months to fully realize the severity and extent. Once the skin re-epithelializes (i.e., wound closure is established and intact), the structural integrity of the injured site should be amenable to most scar treatment protocols, which may then be initiated.
  • Patients undergoing scar treatment should be cautioned to avoid direct sun exposure whenever possible to prevent excess vascular or pigment deposition in the repaired tissue.

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Classification of Scars

  • All scars can be categorized according to both colour and texture (Tables 1 and 2). Both of these components must be considered and addressed independently to attain improvement of the visible quality of the scar.1
  • Active inflammation must first be resolved before determining the correct classification of a scar. Inflammation is characterized by a purple discoloration, tenderness, and focal elevation of the skin.
Scar Colour Features
Red
  • Red scars are due to either persistent inflammation (which should be eliminated before initiation of scar treatment) or dilated capillaries in the dermis.
  • In response to dermal injury, blood vessels dilate in order to provide oxygen, chemical factors, and nutrients necessary for the skin to adequately recover from the injury.
Brown
  • Scars may appear brown due to either melanin or hemosiderin deposition.
  • More melanin is released into the dermis after skin injury in dark-skinned individuals; they are thus more prone to developing post-inflammatory hyperpigmentation.
  • Hemosiderin is deposited due to extravasation of red blood cells where the skin is injured.
White
  • White colour in scars is due to the absence of melanin or dermal fibrosis.
  • Inflammation may partially destroy melanocytes that produce melanin, decreasing pigmentation in a scar.

Table 1: Classification of scars by colour

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Scar Colour Features
Elevated
  • Elevated scars are the result of excessive collagen deposition and fibrosis at the site of skin injury.2
  • Elevated scars can be classified as either hypertrophic or a keloid.
  • Hypertrophic scars show vertical growth only and do not extend beyond the confines of the defect initiating the scar.
  • Keloid scars display both vertical and lateral growth, extending beyond the confines of the defect initiating the scar.
  • Darker skin types are generally more susceptible to the formation of hypertrophic and keloid scars. These skin types may be genetically more prone to collagen deposition post-skin injury.
Depressed
  • Depressed scars may be classified as icepick, boxcar, or rolled in nature.3
  • Icepick scars are usually small (>2mm width), superficial (>1mm depth), and have an acute angle at the base. They typically occur in multiples due to focal collagen injury from prior inflammatory acne.
  • Boxcar scars may appear crateriform as they have right angles. They may be several millimeters in diameter and can be as deep as 2 mm.
  • Rolled scars are larger in diameter with shallow, rolled, nonangled borders. They are often the result of a deep cyst or nodule that has involuted or retracted.

Table 2: Classification of scars by texture

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Treatment Options

  • Every scar can be broken down and categorized according to colour and texture, both of which must be addressed independently to improve the scar's appearance.
  • This paper will focus mainly on topical therapies used to improve the appearance of scars, although tables with comprehensive options for scar revision are presented.

Treatment Options Targeting Scar Colour

Table 3 lists comprehensive options targeting scars with abnormal colour. Topical therapies within each category will be discussed in more detail.

  • Cosmetic camouflage using makeup creams and powders in a patient's normal skin tone will help conceal the abnormal scar colour.
  • Topical vasoconstrictors such as oxymetazoline, epinephrine or cocaine may be used to constrict blood vessels, decreasing a scar's redness.
  • Lightening creams containing hydroquinone, azelaic acid or kojic acid may be helpful to decrease brown hyperpigmentation.
  • Hydroquinone 2%-5% alters conversion of dopa to melanin by inhibiting the activity of tyrosinase. Side-effects include allergic and irritant contact dermatitis, post-inflammatory hyperpigmentation, and cutaneous ochronosis. Animal studies have shown teratogenicity and induction of renal adenoma, but these findings have not been seen in humans.4
  • Kojic acid 2% is a tyrosinase inhibitor produced by fungi such as Aspergillus oryzae. Side-effects may include irritation.
  • Azelaic acid 15% (Finacea®) is a tyrosinase inhibitor and may be antiproliferative and cytotoxic towards melanocytes. Side-effects include erythema, scale, burning, and pruritus.
  • Topical retinoids such as tretinoin 0.01%-0.1% (Retin-A Micro®, Stieva-A®), adapalene 0.1%-0.3% (Differin®, Differin® XP™), and tazarotene 0.1% (Tazorac®) may reduce brown pigmentation by inhibiting tyrosinase transcription, interrupting synthesis of melanin. Side-effects include xerosis, erythema, skin peeling, and sun sensitivity.
  • Chemical peels involve the application of a chemical agent on the skin, causing controlled destruction of parts of the epidermis and dermis, potentially decreasing hyperpigmentation. This leads to exfoliation and later epidermal and dermal regeneration. Common chemical peel agents include alpha hydroxy acids (glycolic acid, lactic acid), beta hydroxy acids (salicylic acid) and trichloroacetic acid. Depth of the chemical peel varies depending on the chemical agent chosen. This should be done in consultation with a dermatologist. Side-effects may include pigmentary changes, infection, erythema, and scarring.5
  • Topical calcineurin inhibitors such as tacrolimus 0.03%- 0.1% (Protopic™) and pimecrolimus 1% (Elidel®) have immunomodulatory effects that may help with repigmentation of white scars. Side-effects include burning and pruritus. Although the US FDA has a black box warning on these therapies regarding risk of lymphoma and skin cancer development, clinical evidence in humans has not suggested causality.6
  • Silicone gels have been shown to reduce the redness of scars.7
Scar Colour Treatment Options
Skin coloured No treatment necessary
Red
  • Topical treatment
    • Vasoconstrictors
    • Camouflage
  • Laser (vascular-targeting)
Brown
  • Topical treatment
    • Lightening creams
    • Topical retinoids
    • Chemical peels
    • Camouflage
  • Physical treatment
    • Microdermabrasion
    • Micropuncturing
  • Laser (pigment-targeting, ablative)
White (hypopigmented or depigmented)
  • Topical treatment
    • Topical calcineurin inhibitors
    • Camouflage
  • Phototherapy
    • UV light therapy (PUVA, UVA1, NB-UVB, BB-UVB)
  • Physical treatment
    • Surgical excision
  • Laser (pigment-stimulating, ablative)

Table 3: Treatment options targeting scar colour1

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Treatment Options Targeting Scar Texture

Table 4 lists comprehensive options targeting scars with abnormal texture. Topical therapies within each category will be discussed in more detail.

  • Elevated scars
    • Strategies for prevention of hypertrophic and keloid scars during surgical procedures include minimizing tension and everting wound edges during closure, avoiding anatomic locations more prone to hypertrophic or keloid scars such as across joints, angle of the jaw, shoulders, mid-chest, and upper back, placing incisions in areas that follow skin creases, and achieving efficient hemostasis.2
    • Very high potency topical corticosteroids such as clobetasol propionate 0.05% (Dermovate®) or halobetasol propionate 0.05% (Ultravate®) ointments or creams may be used for minimally hypertrophic scars. They are usually ineffective with more hypertrophic or keloid scars.
    • Intralesional corticosteroids such as triamcinolone 10-40 mg/mL (Kenalog®) may help decrease the elevation seen in hypertrophic and keloid scars.
    • Corticosteroids act to suppress the immune responses as well as diminish collagen synthesis, inhibit fibroblast growth, and enhance collagen degeneration. Adverse effects of topical and intralesional corticosteroids include hypopigmentation around the injection site, dermal atrophy, telangiectasia, widening of the scar, and delayed wound healing.
    • Topical imiquimod (Aldara™) is an immunomodulator that stimulates interferon-α, inducing collagen breakdown. In off-label use, studies have shown that nightly application of imiquimod to keloidal scars improves cosmetic appearance over an 8-week period. Adverse effects of imiquimod include erythema and irritation.8,9
    • Over-the-counter (OTC) topical silicone gel products (e.g., Kelo-cote® and Dermatix™ Ultra) applied twicedaily for 4 months have also shown beneficial effects on both treatment and prevention of hypertrophic and keloid scars.
      • The postulated mechanism of action involves reducing transepidermal water loss (TEWL), enhancing hydration, and decreasing activation of dermal fibroblasts through inhibition of cytokine production. These combined processes normalize collagen deposition and diminish scar hypertrophy.10
      • Silicone gel may be used for existing and new hypertrophic and keloid scars resulting from burns, surgical procedures, trauma, and wounds. Treatment has been shown to reduce redness, hardness, elevation, itching, and pain.7,10
      • For post-surgical or -trauma treatment, it may be considered a first-line prophylactic strategy in the prevention and development of hypertrophic or keloidal scars.11
      • Both gel and sheet products have comparable efficacy, but for greater practical contouring of flexural areas gels may be preferred, as optimal occlusion is achieved by close apposition of the product with the scar.10
      • The gel is well-tolerated with no common adverse effects.9
      • Spray formulations are especially useful on sensitive or larger skin areas.
      • Preparations containing silicon dioxide dry rapidly, allowing for cosmetics or sunscreen application over the silicone treatment.
    • Occlusive dressings such as pressure dressings and silicone gel sheeting (Cica-Care™) are commonly used to treat burn scars. The mechanism of action is through mechanical compression and reduction in oxygen tension, along with silicone's effects discussed above. Pressure dressings must maintain a pressure of 25-40 mmHg, up to 24 hours a day, for 9-10 months for best results. Silicone gel sheets must be used 24 hours a day for 3-4 months.8,9
    • Topical onion extract (Mederma®) and vitamin E are widely used OTC products for scar revision, but clinical effects were not found to be significant over placebo.9
  • Depressed scars
    • Cosmetic camouflage using makeup creams and powders in a patient's normal skin tone will help fill in and conceal dark shadows created by the scar's depressions.
    • Chemical peels (see treatments for scar colour) serve to exfoliate and resurface the skin's surface, decreasing the relative depth of depressed scars.
Scar Colour Treatment Options
Elevated (hypertrophic or keloid)
  • Topical treatment
    • Topical corticosteroids
    • Topical imiquimod
    • Topical silicone gel
  • Physical treatment
    • Intralesional corticosteroids
    • Intralesional 5-FU
    • Intralesional verapamil
    • Intralesional bleomycin
    • Intralesional interferon-α-2b
    • Occlusive dressings
  • Surgical excision
  • Laser (ablative)
Depressed (icepick, boxcar or rolled)
  • Topical treatment
    • Chemical peels
    • Camouflage
  • Physical treatment
    • Microdermabrasion
    • Dermabrasion
    • Soft tissue fillers
    • Profibrotic agents
    • Volumizing agents
  • Punch and surgical excision
  • Subcision
  • Laser (ablative, non-ablative)

Table 4: Treatment options targeting scar texture1

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Conclusion

  • All scars can be classified by their colour and texture. A multimodal approach targeting both aspects is essential to optimal scar management.
  • Many topical therapies are available to family physicians to improve scar appearance. Failing this, referral to a dermatologist for further topical, physical, light, laser, or surgical interventions for scar revision should be considered.

References

  1. Rao J. Facial Plast Surg Clin North Am 19(2):275-91 (2011 May).
  2. Wolfram D, et al. Dermatol Surg 35(2):171-81 (2009 Feb).
  3. Jacob CI, et al. J Am Acad Dermatol 45(1):109-17 (2001 Jul).
  4. Nordlund JJ, et al. J Eur Acad Dermatol Venereol 20(7):781-7 (2006 Aug).
  5. Khunger N. Indian J Dermatol Venereol Leprol 74 Suppl:S5-12 (2008 Jan).
  6. Patel TS, et al. Am J Clin Dermatol 8(4):189-94 (2007).
  7. Sepehrmanesh M. Komp Dermatologie 1:30-2 (2006).
  8. Juckett G, et al. Am Fam Physician 80(3):253-60 (2009 Aug 1).
  9. Reish RG, et al. J Am Coll Surg 206(4):719-30 (2008 Apr).
  10. Mustoe TA. Aesthetic Plast Surg 32(1):82-92 (2008 Jan).
  11. Mustoe TA, et al. Plast Reconstr Surg 110(2):560-71 (2002 Aug).

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