Mohs Micrographic Surgery, Scar Revision

Anatomy and Physiology

Scars develop as a natural part of the wound healing process, which occurs in 3 distinct phases—inflammation, proliferation, and maturation.[3] Various factors, including patient characteristics, wound location, and surgical techniques, can influence scar formation. Scars may manifest as hypertrophic scars, keloids, widened scars, or contractures, each requiring a tailored approach to management. 

Indications

Scar revision may be considered for various reasons, typically driven by aesthetic or functional concerns. Aesthetic dissatisfaction often arises when scars are prominent, located in cosmetically sensitive areas, or deviate from natural skin tension lines, thereby making them more noticeable.[4] Specific issues include spread scars and hypertrophic scars, which are particularly conspicuous.[5] Discoloration, such as persistent erythema, hyperpigmentation, or hypopigmentation, may also cause significant distress.[6] Additionally, surgical techniques such as flaps and grafts may lead to complications such as pincushion deformity, which is characterized by protruding tissue, especially when flap bodies or grafts are excessively thick or oversized.[7]

Functional impairments are another important consideration for scar revision. Contractures, stiffness, or tethering of adjacent tissues can restrict range of motion and interfere with daily activities.[8] Scars that create tension on free margins may lead to functional issues in anatomical structures, resulting in conditions such as ectropion, eclabium, or external nasal valve incompetence.[3] Pain and discomfort associated with scars can significantly impact quality of life.[9] Patients often report symptoms such as itching, tenderness, or neuropathic pain, particularly with hypertrophic or keloid scars prone to inflammation or ulceration.[10]

When planning scar revision, aligning the procedure with the patient's priorities is essential. Clear communication about the process, expected outcomes, and potential risks is crucial. By addressing both aesthetic and functional concerns while managing expectations, healthcare providers can improve patient satisfaction and overall quality of life.

Contraindications

Relative contraindications include active infection at the scar site, uncontrolled diabetes, or significant comorbid conditions that impair wound healing. Absolute contraindications include known hypersensitivity to anesthetic agents or materials required for revision and scars in areas where revision could result in significant functional compromise.

Additionally, scars located in regions with compromised vascularity or where revision poses an undue risk of functional impairment should be approached cautiously. In cases where there are unrealistic expectations or poor adherence to postoperative care instructions, scar revision may be contraindicated to prevent suboptimal outcomes.

Equipment

Effective scar revision requires access to specialized equipment tailored to the chosen treatment modalities, including essential tools for various interventions.

• Surgical trays: They contain scalpels, forceps, fine scissors, and sutures for procedures such as Z-plasty, W-plasty, and serial excision.

• Injection supplies: They include syringes and fine-gauge needles (eg, 30-gauge) for administering triamcinolone acetonide, fluorouracil (5-FU), or dermal fillers.

• Laser systems: They comprise ablative (CO₂ and erbium:yttrium-aluminum-garnet [Er:YAG]) and nonablative (erbium glass and pulsed-dye [PDL]) lasers for addressing various scar characteristics.

• Microneedling devices: These are equipped with fine needles to create controlled micro-injuries that stimulate collagen production.

• Dermabrasion units: These feature diamond tips or wire brushes for mechanical resurfacing.

• Topical anesthetics: These drugs are necessary for patient comfort during microneedling and other minimally invasive procedures.

• Protective eyewear: They are essential for both practitioners and patients during laser treatments to ensure safety.

• Cooling devices: These are used with nonablative lasers to minimize discomfort and prevent overheating.

• Filler products: They include hyaluronic acid, calcium hydroxylapatite, or poly-L-lactic acid for elevating atrophic scars.

• Radiation systems: These are used for keloid scars in patients at risk of forming keloids. 

Technique or Treatment

Steroids

Triamcinolone acetonide, a commonly used intralesional steroid, exerts its effects by suppressing inflammation and inhibiting collagen synthesis within the scar tissue. By targeting the underlying pathophysiology of hypertrophic scars, steroids help soften and flatten the raised tissue, resulting in a more cosmetically acceptable outcome.[2] Clinical studies have shown that intralesional steroids effectively reduce scar volume, height, and erythema, with minimal adverse effects.[3] The treatment protocol typically involves a series of injections spaced several weeks apart, tailored to the individual characteristics of the scar and the patient's response.[11]

Antimetabolites

Intralesional 5-FU has gained recognition as an effective treatment for hypertrophic and keloid scars. Recent studies highlight its benefits, especially when used in combination with corticosteroids and other modalities such as cryotherapy and laser treatments. The efficacy of 5-FU stems from its ability to inhibit fibroblast proliferation and reduce collagen synthesis, resulting in softer, flatter scars. A recent meta-analysis showed significant improvement in scar appearance with intralesional 5-FU when combined with intralesional corticosteroids, reporting better outcomes compared to corticosteroid monotherapy.[12]

Ablative and Nonablative Lasers

Laser technology offers a diverse array of modalities for scar revision, each targeting specific aspects of scar tissue. These modalities include ablative and nonablative lasers, fractional laser therapy, PDLs, and intense pulsed light (IPL) therapy.

• Ablative lasers: These lasers include the 10,600 nm CO₂ and 2940 nm Er:YAG lasers, which work by removing superficial layers of skin, stimulating collagen remodeling, and smoothing irregularities in scar texture.[4] Fractional ablative lasers, which create microscopic columns of thermal injury within the skin, are particularly effective for treating atrophic scars and improving overall skin texture to improve the appearance of prominent scars.[4] 

• Nonablative lasers: These lasers include the 1550 nm erbium glass laser and the 1540 nm fractional erbium-doped fiber laser, which deliver heat energy to the deeper layers of the skin without causing visible damage to the surface.[5] These lasers promote collagen production and tissue remodeling, making them suitable for treating hypertrophic scars and improving skin laxity.[5] PDLs emit high-energy light in the 585 to 595 nm range, which is selectively absorbed by hemoglobin within blood vessels, thereby making them ideal for targeting vascular components of scars.[6] PDL therapy effectively reduces erythema and vascularization in hypertrophic scars and keloids, thereby improving scar appearance.[6] IPL therapy utilizes broad-spectrum light in the 500 to 1200 nm range to target melanin and hemoglobin in the skin, offering a versatile approach to scar revision.[7] IPL therapy can improve pigmentation irregularities, erythema, and vascularization associated with scars, resulting in a more even skin tone and texture.[7]

Microneedling

Microneedling has emerged as a promising technique for scar revision, offering a minimally invasive approach to improve the appearance of scars. This procedure involves the use of a device equipped with fine needles to create controlled micro-injuries in the skin, which stimulates collagen production and promotes tissue remodeling. Recent studies have demonstrated that microneedling is effective in improving the appearance of various types of scars, including acne, surgical, and traumatic scars. A recent study demonstrated that microneedling significantly improved both the aesthetic appearance of scars and patient satisfaction.[8] Platelet-rich plasma is commonly combined with microneedling, particularly for the treatment of atrophic acne scars; however, data on its effectiveness for surgical scars remain limited.[9]

Dermabrasion

Dermabrasion is a well-established technique for scar revision, especially effective for superficial to moderately deep scars. The procedure involves the mechanical abrasion of the skin's surface using a rotating instrument with a diamond tip or wire brush, which removes the outer layers of skin and stimulates collagen production.[10] Recent studies have supported the efficacy of dermabrasion in improving the appearance of various scars, including acne scars, surgical scars, and traumatic scars.[10]

Surgical Revision

Surgical scar revision techniques are key interventions for dermatologists and plastic surgeons to improve both the appearance and functionality of scars. 

• Z-plasty: This is a versatile geometric flap technique commonly used to change the direction of scars, redistribute tension, and enhance scar aesthetics. This procedure involves making Z-shaped incisions and transposing the resulting triangular flaps.[13] 

• V to Y repair: This versatile technique, also known as the V-Y advancement flap, is used for revising scars with limited tissue mobility or tension. This technique involves creating a V-shaped incision and converting it into a Y-shaped flap, allowing for tissue advancement and scar relaxation.[14] The V-Y advancement flap is particularly effective in cases of ectropion and eclabium. 

• Serial scar excision: This technique involves the sequential removal of scar tissue, which is followed by meticulous wound closure. Serial scar excision is particularly effective for linear scars, as it allows for precise scar alignment and tension redistribution. Recent advancements in serial scar excision techniques have focused on optimizing scar outcomes and minimizing the risk of scar recurrence.[15] 

• W-plasty: This is a geometric flap technique designed to break up linear scars and enhance their camouflage. W-plasty involves creating W-shaped incisions, allowing scar relaxation and tension redistribution. Recent advancements in W-plasty have focused on optimizing scar outcomes and reducing scar visibility.[13] 

• Broken line closure: This technique involves creating irregular incisions along the scar margins to disrupt scar continuity and blend the scar edges with surrounding skin. Broken line closure technique is particularly useful for revising wide or irregular scars, enhancing scar camouflage, and minimizing visibility.[13]

Dermal Fillers

The use of dermal fillers for treating atrophic depressed scars has shown promising results in recent years. Fillers such as hyaluronic acid, calcium hydroxylapatite, and poly-L-lactic acid are commonly used to elevate depressed scars, improving their appearance by bringing them to the level of the surrounding skin. A recent study demonstrated that hyaluronic acid fillers significantly enhance the texture and appearance of atrophic scars, with patients reporting high satisfaction rates and minimal adverse effects.[16] Additionally, another study highlighted the effectiveness of calcium hydroxylapatite fillers in providing both immediate and long-lasting improvements in the appearance of atrophic scars compared to a placebo.[17] 

Combination Therapy

Combination therapy is commonly used in cases of hypertrophic scars or keloids. Intralesional 5-FU can be combined with corticosteroids, with doses administered concurrently for enhanced effectiveness.[18] Imiquimod, on the other hand, has limited supporting evidence due to its tendency for collagen breakdown. Additionally, as keloids often persist after laser treatment alone, combining intralesional triamcinolone or 5-FU with ablative lasers (CO₂ or Er:YAG) can have improved results compared to monotherapy.[19]

Radiation Therapy

Radiation therapy has long been used as an adjunctive treatment for keloid scars, particularly following surgical excision, to reduce the risk of recurrence. While its role in keloid management is well-established, its application in Mohs surgery is less defined. However, due to its effectiveness in preventing keloid recurrence, postoperative radiation may offer a promising avenue for future research, particularly for optimizing outcomes in high-risk cases following Mohs surgery.

Complications

Complications can arise with any invasive procedure, and the benefit-to-risk ratio should be carefully evaluated by the physician. For steroid injections, cutaneous atrophy may occur beyond the area of hypertrophic scarring, further accentuating the asymmetry.[20] On the other hand, antimetabolite injections can lead to erosions, ulceration, or edema.[21]

Ablative lasers carry the risk of skin irritation, infection, and, rarely, ocular injury.[22] More invasive procedures, such as microneedling and dermabrasion, can increase the risk of pigmentary changes, potentially offsetting the benefits of texture improvement in scar revision.[23] Finally, surgical revision inherently carries the risk of worsening the appearance of the existing scar; therefore, careful patient selection and technique are crucial considerations for the physician.

Clinical Significance

Scar revision is clinically important for improving the appearance, texture, and function of scars, ultimately enhancing patients' quality of life. In addition, it addresses both aesthetic concerns and functional limitations caused by scars from MMS. Healthcare providers can reduce scar visibility, restore skin contour, and improve scar flexibility by utilizing various scar revision techniques. In addition to cosmetic benefits, scar revision can alleviate symptoms associated with keloids or hypertrophic scars, such as itching, pain, and restricted movement.

Enhancing Healthcare Team Outcomes

Patients undergoing MMS are at risk of developing various scar deformities that may require revision treatment. Accurate identification and management of these complications are crucial to reducing associated morbidity. Scar revision demands a collaborative approach among healthcare professionals to optimize patient outcomes. Interprofessional healthcare providers, including dermatologists, plastic surgeons, primary care providers, advanced practitioners, nurses, medical assistants, and other team members involved in patient care, should be well-equipped to recognize and address MMS scar complications using appropriate scar revision techniques.