Hypertrophic scarring and keloids following burn injuries

INTRODUCTION — Keloids and hypertrophic scars are aberrations of physiologic wound healing characterized by greater and more sustained extracellular matrix deposition. They may also develop following any insult to the deep dermis.

The early application of topical therapies is advocated for healed burns in an effort to prevent hypertrophic scarring, particularly for deep burn injuries or those that show signs of delayed healing. The role of pressure garment therapy is less clear.

Keloids and hypertrophic scars affect the patient's quality of life, both physically and psychologically, causing pain, pruritus, and contractures. As such, burn patients should be promptly referred to a surgeon experienced in burn care if the wound fails to begin reepithelialization by two weeks, or at the first sign of hypertrophic scarring.

The evaluation and treatment of keloids and hypertrophic scars that result from burn injury is reviewed here. The initial management of the burn wound is reviewed separately. (See "Overview of the management of the severely burned patient".)

INCIDENCE AND RISK FACTORS — Hypertrophic scars occur in between 30 and 90 percent of patients following burns [1-3]. A longer time to heal (ie, prolonged inflammation at the wound site) is the most important risk factor [2,4-6]. As an example, in a retrospective review of 59 children and 41 adult burn patients, when the time to heal was between 14 and 21 days, one third developed hypertrophic scars [4]. However, when the burn wound healed after 21 days, 78 percent of patients developed hypertrophic scars. For this reason, as well as for reduction of other burn wound complications (eg, infection), early rather than later burn wound excision and grafting is preferred for deep burns.

During skin grafting, the use of mesh skin grafts with a high expansion ratio (>1:2) may increase the risk for pathologic scarring but may be necessary in patients with extensive burns, where coverage is the priority. Use of dermal regeneration templates may improve aesthetic and functional outcomes. (See "Overview of the management of the severely burned patient", section on 'Early burn excision and coverage' and "Overview of surgical procedures used in the management of burn injuries", section on 'Burn wound coverage'.)

Other risks for hypertrophic scarring include deep full-thickness burns, location of wounding (shoulders, anterior chest, neck, upper arms, cheeks), darker skin tone, and wounding during puberty and pregnancy. Genetic susceptibility, as evidenced as a personal or family history of exuberant scars after injury, also contributes to excessive scar formation [2,7,8].

CLINICAL ASSESSMENT

Pathologic versus typical scarring — Following skin injury, normal wound healing progresses through a series of defined phases, which ultimately restore skin integrity through the creation of a scar. Burn wounds can heal by primary or secondary intention (eg, skin grafts) depending on their depth and need for coverage. (See "Basic principles of wound healing".)

Normal scars progress from immature and mature (table 1). Mature scars are flat and essentially asymptomatic. Typically, the average time for scar maturity is 9 to 12 months. Thus, any scar less than one year old can be described as an immature scar. Immature scars may mature over time; however, some scars will develop symptoms (eg, pain, pruritus) and/or develop characteristics consistent with hypertrophic or keloid scars. It can be difficult to determine when an immature scar becomes a hypertrophic scar. There is a wide range of changes between the scar that becomes hypertrophic in the first few months after the burn is healed compared with the more severe hypertrophic scar that becomes disfiguring [9,10].

Excessive scars form as a result of aberrations of physiologic wound healing and may arise following any insult to the deep dermis [11]. The characteristics of the scar determine if it is developing into a keloid or a hypertrophic scar (table 1) [9,10,12-15]. Histologically, hypertrophic scars and keloids contain an overabundance of dermal collagen. (See "Keloids and hypertrophic scars", section on 'Diagnosis'.)

●Hypertrophic scarring is defined as a scar raised above the skin level that remains within the confines of the original area of skin injury and appears to be due to an overproduction of collagen and an imbalance between the anabolic and catabolic phases of healing [2,12,16]. On histological examination, hypertrophic scars contain primarily type III collagen oriented parallel to the epidermal surface with abundant nodules containing myofibroblasts, large extracellular collagen filaments, and plentiful acidic mucopolysaccharides [17]. Hypertrophic scars can be linear or widespread. Those associated with burn wounds are predominantly widespread.

●Keloids also rise above the skin level, but these extend beyond the margin of the initial skin injury. Minor keloids are those <0.5 cm; larger keloids are termed major keloids. Keloid tissue is mostly composed of disorganized type I and III collagen containing pale-staining hypocellular collagen bundles with no nodules or excess myofibroblasts [17,18].

Scar grade — Many assessment tools are available for analysis of pathologic conditions of the skin; however, there is no general agreement on the most appropriate tools for evaluation of scar tissue [19].

Scars are graded based upon specific parameters that include pigmentation, vascularity, thickness, pliability, height or depression, patient acceptability, and comfort. A variety of measuring tools have been developed, including the Vancouver Scar Scale (VSS), the Visual Analog Scale (VAS), and the Patient and Observer Scar Assessment Scale (POSAS).

●Scar grading systems are generally used to quantify alterations in scar appearance during treatment, typically in a clinical research setting. Although individual scar rating scales and other available tools have value, they generally are lacking in terms of validity, clinical evidence, and fulfillment of clinometric requirements [20-22]. In addition, grading scales have acceptable consistency and reliability but have limited sensitivity and are at least partially subjective in nature [20].

●An advantage of the POSAS relative to other scales is the inclusion of patient assessment, which is considered an important aspect of scar evaluation [22]. The POSAS is also more consistent and reliable than the widely used VSS [20,21]. Given the natural course of scar improvement during healing, the use of any scale must include the parameter of time relative to initial scar formation or subsequent treatment intervention [22].

For routine clinical practice, evaluation of scar size, thickness, symptom severity (eg, pain, itching), and patient concerns is advised before initiating any treatment plan. Subsequently, an intraindividual comparison between baseline and later time points is advised, and objective changes in scar height and volume after different treatment approaches can be noted, avoiding subjective influences on scar evaluation [23].

Quantitative three-dimensional imaging is a promising method for quick and objective assessment and documentation of abnormal scars and their response to treatment within routine clinical practice. In one study, three-dimensional stereophotogrammetry was used to objectively quantify a mean scar volume reduction from 0.73 to 0.14 cc following intralesional therapy [24].

Quality of life — Keloids affect the patient's quality of life, both physically and psychologically [11,25,26]. A complete assessment of the impact of the scars on the burn patient should include a quality of life assessment. Several tools have been specifically designed for patients with hypertrophic scars or keloids [27-29]. Validation of these tools have shown excellent correlation with pain, pruritus, and restriction of mobility.

The Dermatologic Life Quality Index (DLQI) has also been used to evaluate daily impairments of life quality of different scar types [30].

PREVENTIVE STRATEGIES AND THEIR EFFICACY — Once the wounds are closed (ie, epithelium of the burned skin or skin graft is intact and stable), scar prevention should be initiated. Prevention of widespread hypertrophic scarring is more efficient than treatment of a scar once it has matured [9,10]. (See 'Timing' below.)

The treatments discussed below (table 2) are used to prevent or reduce the risk of hypertrophic scarring or keloid formation in the fresh scar that develops following a partial-thickness, full-thickness, or deeper burn (figure 1). Some of these same treatments are also used to manage established hypertrophic scars and keloids. (See 'Clinical algorithms' below.)

●Silicone sheet or gel or onion-extract-containing gel is applied after burn wound coverage or closure for approximately three to six months. (See 'Silicone sheets and gel formulations' below and 'Onion extract gels' below.)

●Compression garments may be used as monotherapy or in combination with silicone gel or sheets for up to one year [31]. (See 'Compression therapy' below.)

●If there is no improvement with either application, consideration should be given to pulsed-dye laser (PDL) therapy to reduce wound erythema or fractional ablational laser therapy to improve scar surface and pliability. (See 'Laser therapy' below.)

Silicone sheets and gel formulations — Silicone gel sheeting, a soft, slightly adherent, and semiocclusive covering, may prevent or reduce the formation of hypertrophic scars by decreasing the collagen remodeling phase of wound healing, although the exact mechanism is unclear [2,32-35]. It has been suggested that its effect is due to increased wound hydration [36,37]. Only immature scars should be treated with gels or gel sheets as mature burn scars have not been shown to respond [32].

Silicone sheets are applied starting approximately two weeks after burn wound closure for 12 to 24 hours per day for approximately 12 to 24 weeks [38]. Silicone products can be used in children and are not painful [6]. Side effects of silicone sheeting include local skin reactions, such as maceration and pruritus, which may necessitate temporary cessation [32]. In areas where silicone sheets will not conform to the shape or size of the burn wound, silicone gel can be used to reduce the risk of unpleasant scarring and erythema and to improve scar pliability [39].

Most trials evaluating silicone sheets for prevention have been in the non-burn population. In a meta-analysis of five trials including 402 non-burn patients at risk for hypertrophic scarring (mostly patients with surgical wounds), the rate of abnormal scarring was lower with silicone gel sheeting compared with control, but the difference was not statistically significant (15 versus 21 percent; risk ratio [RR] 0.55, 95% CI 0.21-1.45) [40]. In a subgroup analysis of 51 "high-risk" patients (people who were prone to scarring), the rate of hypertrophic scarring was significantly lower in the silicone gel sheeting group (24 versus 54 percent; RR 0.46, 95% CI 0.21-0.98). Most of the trials included in the meta-analysis were judged to be at high risk of bias.

Among studies performed in burn-only patients [31,41-44], most include a small number of participants, have differing comparisons, and are poorly controlled [32]. Larger randomized trials are needed to confirm the benefits of silicone products as a prevention and treatment of hypertrophic scars following burns.

Onion extract gels — An alternative therapy to silicone is onion extract gel; however, the evidence supporting this therapy for prevention of scarring is inconclusive and conflicting, with most trials in non-burn populations [40,45-49]. In one small trial that compared onion extract with silicone products (gel, gel sheet), the cosmetic appearance of burn hypertrophic scars was worse with onion extract gel after six months from injury as measured by the Vancouver Scar Scale [42]. Nevertheless, onion-extract-containing scar gels are generally well tolerated and are used worldwide, alone or in combination, for the prevention of excessive scar formation post-burn.

Compression therapy — Pressure therapy, in the form of continuously worn garments, may decrease collagen synthesis by limiting the supply of blood, oxygen, and nutrients to the scar tissue and/or by increasing apoptosis [11,50,51]. Although the efficacy of pressure therapy remains unproven in clinical trials [52-56], the practice is supported by years of clinical experience as a routine component of burn management. In a systematic review and meta-analysis of six randomized controlled trials (316 patients), pressure garment therapy reduced scar height, though the difference was small and of questionable clinical significance (standardized mean difference -0.31, 95% CI -0.63 to 0.00) [52]. There were no differences in global scar appearance, vascularity, pliability, or color. Three trials examining the combined use of pressure and silicone sheets have conflicting results [31,44,57].

We mostly use pressure garments after burns affecting the arms and legs, rarely on the trunk. The amount of pressure and the duration of the therapy are based upon observational studies. We advise continuous pressure of 15 to 40 mmHg for at least 23 hours per day for at least 12 months while the burn scar is actively remodeling, adjusted for patient comfort and effectiveness [53,58]. The duration of wearing garments can also be extended up to 24 months. A randomized trial that included 53 hypertrophic scars from 17 patients found that patients treated with pressure garments providing 20 to 25 mmHg of pressure had significant improvement in scar thickness and erythema compared with wounds treated with 10 to 15 mmHg of pressure [54].

The use of compression therapy is limited by the ability to adequately fit the garment to the wounded area [58]. Specialized suits or bandages, sometimes with transparent plastic masks or pressure buttons, may be needed for special locations. Compliance is often reduced by patient discomfort and other side effects such as maceration, eczema, drainage, or odor emanating from the garment.

Investigational therapies — Investigational approaches include the use of gene transfer technology to promote wound healing to stimulate the granulation process, vascularization, and reepithelialization or the scar quality [59,60]. Additional studies are needed to define growth factor levels in different phases of wound healing and to elucidate the precise timing of gene expression or downregulation required to better augment wound healing and control scar formation [61].

GENERAL APPROACH TO TREATMENT — There are no established criteria that identify patients as ideal candidates for treatment. Even patients with a personal history of keloid scarring from other events may be eligible for attempts at scar modification, but recurrence of excess scarring is more likely. (See 'Incidence and risk factors' above.)

Goals — Treatment goals should be individualized based upon symptoms (eg, pruritus, pain), functional impairment (eg, contracture, mechanical irritation), and aesthetics [9,10,62]. Marked improvement is the main goal of treatment. This should include scar volume reduction by 30 to 50 percent, symptom reduction >50 percent, and/or sufficient satisfaction of the patient, which should be achieved after three to six treatments or after three to six months.

Timing — The timing of treatment is an important component of scar modification. Clinical experience supports the observations that younger scars respond better to any treatment approach compared with matured scars. However, hypertrophic scars have a prolonged maturation phase, meaning that they may improve over a one-year period by themselves and can show significant flattening and softening [63]. Early intervention using minimal invasive treatments may be useful, but surgical interventions should generally be delayed for at least one year. After that, revision of hypertrophic scars or keloid scars that are not causing functional impairment can generally proceed electively. (See 'Scar excision' below.)

Any functional impairment due to scar contractures should be managed as soon as it is identified. Hypertrophic scar contractures involving joints should be released as early as possible, to improve mobility [26,64]. Keloids rarely cause contractures. (See 'Contracture release' below.)

Principles of treatment — A few general principles are fundamental to the optimal management of hypertrophic scars and keloids that develop following a burn injury. These include the following [9,10,26,31,38,63,65]:

●Treatment cannot be standardized because of the many clinical variables relating to hypertrophic scar and keloid formation. These include:

•Scar location

•Patient age

•Type of scar

•Ethnic and genetic predisposition

●Personalized management is necessary using a combination of therapies to achieve the desired results. A patient history of scarring and prior treatment can help determine the likely effectiveness of specific treatments for that patient.

●Treatment options include silicone gel sheeting, other topical therapies, intralesional injection therapies, laser therapy, compression therapy, massage therapy, physical therapy, and surgical scar excision and reconstruction. No single method of scar treatment can provide scar reduction, improve function, and/or alleviate symptoms for every patient.

●Treatmentis based upon the type or characteristics of the scar(s) (table 1 and table 2) [9,10,38]. Smaller hypertrophic scars or keloid scars are candidates for injectables. Scars that involve a large surface area are better treated with silicone sheets or compression garments.

•Patients with painful or pruritic scars can be initially managed using preventive therapies to minimize excessive scarring, such as silicone gel sheeting, onion extract gel, or compression therapy. (See 'Preventive strategies and their efficacy' above.)

•A trial of topical agents such as moisturizers and topical or intralesional corticosteroids may be useful. Antihistamines may be added to relieve pruritus [9,10]. (See "Management of burn wound pain and itching", section on 'Treatment of pruritus'.)

•If these measures are not successful at meeting the goals for treatment, additional options include laser therapy, or surgical scar revision and reconstruction. (See 'Laser therapy' below and 'Radiation therapy' below and 'Surgery' below.)

•Postoperative radiotherapy or pharmacologic therapy using fluorouracil (FU) or triamcinolone acetonide (TAC) following surgical scar revision and reconstruction may help prevent recurrence. (See 'Intralesional pharmacologic therapy' below.)

●Special patient populations also require specific considerations for treatment.

•Children – Most hypertrophic scars and keloids are managed with silicone-based topicals or sheets or pressure garments. Intralesional agents are generally avoided because children are susceptible to side effects that include lipoatrophy, blistering, and pain.

•Pregnant women – High-risk therapies (eg, FU, radiation therapy) are avoided. (See "Radiation-related risks of imaging", section on 'Pregnant women'.)

•Facial scars – Crystal suspensions (eg, TAC) are avoided as they increase the risk of lipoatrophy.

EFFICACY OF TREATMENTS IN BURN SCARS

Intralesional pharmacologic therapy — Intralesional pharmacologic treatments for the treatment of hypertrophic scarring and keloids include predominantly triamcinolone acetonide (TAC) and fluorouracil (FU) [9,10]. Factors that influence reported outcomes include the length of follow-up, the nature of the scars being treated, and whether there was a control therapy for comparison [9,10]. The majority of trials are in non-burn populations. Additional high-quality studies in the burn population are needed to identify the optimal agents, dosing, and timing. (See "Keloids and hypertrophic scars" and "Keloids and hypertrophic scars", section on 'Intralesional chemotherapeutic agents'.)

Repeated injections of TAC (40 mg/mL), alone or in combination with other intralesional therapies, administered at weekly or monthly intervals for four to six months appear to improve burn scar characteristics [66-69]. Alternatively, intralesional FU (50 mg/mL) is another approach to treatment. Two trials [66,70] identified in a systematic review suggest that intralesional verapamil (2.5 mg/mL) may be as effective as TAC with fewer adverse effects [71]. However, in a later trial, recurrence rates for verapamil were higher when compared with TAC [72].

Intralesional therapies have also been used in combination with each other and with other treatments for refractory lesions [65,73,74]. (See 'Surgery' below and 'Other treatments' below.)

Surgery

Contracture release — Increased tension on burn wound margins can result in the development of hypertrophic scars. Early surgical release is the most promising option based upon our clinical experience. Effective release of wound tension can be achieved by using a Z- or W-plasty (not appropriate for immature hypertrophic scars), full- or split-thickness skin grafts, or local skin flaps [38,75,76]. The optimal approach depends upon the degree of tension, the surface area involved, and the individual preference and expertise of the surgeon. (See "Z-plasty" and "Skin autografting" and "Overview of flaps for soft tissue reconstruction".)

Prior to early contracture release, an early intervention of anti-inflammatory agents or radiotherapy may reduce recurrence rates. Some experts advocate using TAC or FU initially to soften the scar tissue prior to contracture release.

Scar excision — Hypertrophic scar or keloid excision alone is not an effective approach, since recurrence rates are high, ranging from 45 to 100 percent [38,77,78]. Scar excision should only be used in conjunction with other treatments applied before or after (or both) scar excision to reduce the risk of excessive scar formation [9,10]. One preoperative approach that may reduce recurrence is to inject cortisone or FU prior to surgery until the keloid or hypertrophic scar is stabilized and then perform the surgery. This approach may be less effective in pediatric burns [79]. Another approach uses radiotherapy before and after keloid excision [80]. (See 'Intralesional pharmacologic therapy' above and 'Other treatments' below.)

It is hypothesized that performing surgery when the scar is inactive will help reduce recurrence. However, for hypertrophic scars and keloids that develop because of delayed wound healing (eg, deep dermal burn, burn wound infection), surgical excision with primary suture closure or coverage with a skin graft converts the site into a fresh wound, potentially reducing the likelihood of hypertrophic scar formation at that site [38,81].

Other treatments

Laser therapy — Several types of lasers have been used in the treatment of keloids and hypertrophic scars following burn injury, including the fractional CO₂ laser, pulsed-dye lasers (PDLs), and erbium or neodymium-doped yttrium aluminium garnet (erbium:YAG and Nd:YAG) lasers [82]. Laser treatment (particularly fractional ablation type), often in combination with local flap design and/or the application of intralesional agents, is increasingly being advocated [83,84]. Patient satisfaction is generally high. The principles of using lasers in burns and burn reconstruction is reviewed separately. (See "Overview of lasers in burns and burn reconstruction".)

●PDL therapy was the first to gain wide acceptance for the management of hypertrophic scars and keloids and is the standard of care in some major burn centers [15]. The primary mechanism of PDL therapy is destroying small blood vessels by photothermolysis. PDL treatments can improve the appearance and normalize the vascularity and pliability of postoperative scars. Both long- and short-pulse PDL treatments are safe and improve the quality and cosmetic appearance of new surgical scars [85,86]. However, PDL therapy appears to be more effective for preventing hypertrophic scars, rather than for treating established scars [2,15]. Nonoverlapping laser pulses at fluences ranging from 6.0 to 7.5 Joules/cm² (J/cm²; 7 mm spot) or from 4.5 to 5.5 J/cm² (10 mm spot) are used for the treatment of hypertrophic scars and keloids [87]. Two to six treatment sessions are necessary to successfully improve scar color, height, pliability, and texture [88]. However, other authors have not been able to reproduce these findings [89]. Nevertheless, based upon the German guidelines on scarring [38], PDL can be used for reduction of erythema (eg, in fresh, highly vascularized, reddish scars) and may also be considered for improvement of severe pruritus.

●The 532 nm Q-switched Nd:YAG laser and the 585 nm flashlamp-pumped pulsed dye laser (FLPDL) offer comparable and favorable results for the treatment of pigmented hypertrophic scars. The 532 nm Q-switched Nd:YAG laser may be preferred by patients distressed by the dark color of their scars [90]. In addition, the higher penetration depth of the 532 nm Q-switched Nd:YAG laser may be more suitable for thicker scars compared with PDL treatment. Multiple treatments every three to four weeks using an Nd:YAG laser (5 mm spot size diameter, 14 J/cm² energy density, 300 microsecond exposure time per pulse, and 10 Hz repetition rate) are effective for improving hypertrophic scars and keloids. The authors of one study suggest that the Nd:YAG laser is most suitable for keloids and hypertrophic scars that have just appeared and/or have remained small and thin [91].

●Fractional lasers might play a promising role in the treatment of widespread burn scars. Improvements in both clinical and structural features of burn scars have been reported after fractional CO₂ laser procedures [92-95]. In a large prospective study, fractional CO₂ laser therapy improved the signs and symptoms of hypertrophic burn scars, as measured by objective and subjective instruments [96]. In another review, patient satisfaction with fractional CO₂ laser therapy was 96.7 percent [97]. Patients reported reductions in neuropathic pain, tightness (contracture), and pruritus after approximately three treatments. In one small study, although multiple treatment sessions were needed for completely satisfying results, a single treatment demonstrated significant improvement of Vancouver Scar Scale (VSS), Dermatologic Life Quality Index (DLQI) and Patient and Observer Scar Assessment Scale (POSAS) scores compared with baseline. Fractional lasers are also associated with significant surface relief improvements and reductions in scar firmness compared with untreated internal controls [92]. Regardless of these promising results, more in-depth studies are needed to evaluate clinical protocols before definite recommendations for settings and intervals in between treatment sessions can be made [9].

Radiation therapy — Superficial X-rays, electron beams, and low- or high-dose-rate brachytherapy have been used with overall good results to reduce recurrence of hypertrophic scars in burn patients [98-101], excepting one report [102]. In general, radiotherapy in association with surgical excision is performed for selected patients with a high risk of recurrence (eg, dark skin type, multiple keloids, areas of high tension).

Electron beam irradiation should be started early (24 to 48 hours) after keloid excision. A total dose of usually 12 Gy in 6 or 10 fractions of 2 Gy applied daily or every second day is currently recommended by dermatologists [38].

Cryotherapy — Most data available for cryotherapy relate to intralesional cryosurgery for keloids [98,103,104]. The probe, which is inserted into the hypertrophic scar or keloid, is connected to a canister of liquid nitrogen, which causes the cryoneedle to freeze, thereby freezing the scar tissue from the inside out. An average reduction in scar volume of 51 percent can be achieved following a single cryotreatment. For widespread burn scars, this approach is very time consuming, which limits the usefulness of this therapy.

Spray cryotherapy can be used for hypertrophic scars or keloids and is frequently used in combination with intralesional pharmacologic therapies. When treatment is combined, cryotherapy should be performed prior to injections to soften the tissue and ease the injection [105].

Massage therapy — There is preliminary evidence to suggest that scar massage may improve hypertrophic burn scarring. Systematic reviews have identified eight studies suggesting improvements in scar characteristics and reduced pain and itching [106-109] but noting that the quality of evidence is poor and there is a lack of consistent and valid scar assessment tools [110]. (See 'Clinical assessment' above.)

CLINICAL ALGORITHMS

Immature scar, erythematous hypertrophic scar, minor keloid — The first line of treatment for immature burn scars, erythematous hypertrophic burn scars, and minor keloids following burns includes (table 2) [111-113]:

●Triamcinolone acetonide (TAC) injections administered every three to four weeks up six times (ie, six months). TAC can be used alone or in combination with silicone gel or silicone sheets [9,10,114]. Occasionally, injections continue for six months and more, depending upon the response [115]. (See 'Intralesional pharmacologic therapy' above.)

●Combination of silicone gel or sheeting with monthly intralesional corticosteroid injections (10 to 40 mg/mL) [9,10,38]. (See 'Silicone sheets and gel formulations' above.)

●Pressure dressings can be applied for approximately three weeks to reduce the risk of progression of keloids. (See 'Compression therapy' above.)

For burn scars that do not favorably respond to the first line of therapy, spray cryotherapy with TAC injections can be administered three to six times every four weeks, or intralesional cryotherapy can be attempted twice, which is usually used for older or larger keloids prior to injection to soften the tissue and ease the injection [26]. (See 'Cryotherapy' above.)

If response is still not adequate, the third-line management options include fluorouracil (FU) with TAC every week until the scar is flattened, repeat intralesional cryotherapy, or a surgical excision with a silicone product. Intralesional FU is an effective modality to treat minor keloids [116]. (See 'Intralesional pharmacologic therapy' above.)

Persistent erythematous wounds are treated with pulsed dye laser (PDL). (See 'Laser therapy' above.)

Immature scars should not be excised unless there is evidence of functional impairment, increased tension on wound margins, or delayed epithelialization. Surgical excision alone is reserved for patients with minor keloids that cause significant functional impairment, increased tension on wound margins, or delayed epithelialization or who have failed other modalities. However, some patients request removal of the minor keloid rather than undergoing medical management. Given the potential for recurrence after surgical excision of minor keloids, patients should be counseled regarding their expectations and possible outcomes. In addition, partial excision of the keloid is preferred if full excision increases the risk of structural damage or deformity [9,10]. Response rates vary from 50 to 100 percent and recurrence rates from 9 to 50 percent [77]. Adverse events include dermal atrophy, telangiectasia, and pain at the injection site. In addition, excisions of a keloid scar may result in a longer scar than the original and can result in an even larger keloid [77,78]. (See 'Scar excision' above.)

Widespread hypertrophic burn scar — Widespread hypertrophic scars can be a challenge to manage, and, frequently, individualized counseling and treatment plans need to be developed to address issues that include function (eg, joints) and cosmesis. The treatment of widespread hypertrophic burn scars depends on whether tension is present in the wound (table 2).

Hypertrophic scarring that results from excessive wound tension or a delay in healing (eg, infection) is optimally managed with surgical release and scar excision followed by use of silicone gel sheets [9,10]. (See 'Silicone sheets and gel formulations' above.)

Onion-extract-containing formulations may also be used, although the body of evidence is not robust. (See 'Onion extract gels' above.)

The use of pressure garments has been standard therapy for widespread hypertrophic burn scars for many years. (See 'Compression therapy' above.)

PDL therapy can be used to treat the erythema in widespread hypertrophic scars. If there is no improvement, ablative CO₂ fractional lasers may be a promising alternative approach. In general, the PDL target is the erythema, and eventually there is some improvement of pliability of the scar. With a CO₂ laser, small columns (ablative microscopic treatment zones) are created that lead to microscopic wounds from which the wound healing process is activated. The claim is that due to remodeling of the tissue architecture and a shift of different collagen subtypes, the scar is being improved. Fractional ablation laser techniques have the advantage of performing well on large plates of hypertrophic scar, a clinical problem that is otherwise difficult to manage. (See 'Laser therapy' above.)

Refractory or recurrent major keloids — Refractory or recurrent major keloids present a management challenge as they are often recalcitrant to treatment and have a high probability of recurrence if they are excised [9,10,114,117]. Treatment of recurrent keloids and hypertrophic scarring following apparently successful treatment is similar to initial therapy; however, subsequent treatment may be more aggressively approached or by using combination treatments.

Intralesional corticosteroid administration with or without intralesional or spray adjuvant cryotherapy is advocated as a first-line strategy for patients with refractory or recurrent keloids [9,10]. If this strategy is not effective within three to four months, transition to intralesional FU and TAC is suggested [9,10,65,73,74,118]. The author advocates spray cryotherapy and TAC for a major keloid from a burn. The regimen at a major burn center in Canada is to inject either FU in low doses of 10 mg/mL or high doses of 40 mg/mL using triamcinolone 40 mg/mL [119]. The injection is conducted every four weeks for three to six months.

Secondary and tertiary management options for refractory keloids include laser treatment and surgical excision with appropriate prophylactic intralesional therapy, or radiation therapy. Whenever possible, referral to a clinician with expertise in managing recurrent or refractory keloids is advised.

SOCIETY GUIDELINE LINKS — Links to society and government-sponsored guidelines from selected countries and regions around the world are provided separately. (See "Society guideline links: Care of the patient with burn injury" and "Society guideline links: Keloids and hypertrophic scars".)

SUMMARY AND RECOMMENDATIONS

●Clinical assessment – Classification of excessive burn scarring is important to management (table 1). Mature scars are flat and essentially asymptomatic. Immature scars may mature over time; however, some scars will develop symptoms (eg, pain, pruritus) or develop characteristics consistent with a hypertrophic scar or keloid. (See 'Pathologic versus typical scarring' above.)

●Prevention of excessive burn scarring – Once the wounds are healed (ie, epithelium of the burned skin or skin graft is intact and stable; typically around two weeks after the injury), scar prevention measures should be initiated. For most patients, we suggest silicone sheeting or gel in combination with pressure therapy (if practical) (Grade 2C). Onion extract is a reasonable alternative to silicone, but it may be less effective. Prevention measures should generally be continued for three months (table 2). Use of compression therapy may be limited by patient discomfort and other side effects. (See 'Preventive strategies and their efficacy' above.)

●Goals and treatment – The goals of treatment for established hypertrophic scars or keloids include reduction of scar volume by 30 to 50 percent, reduction of symptoms by >50 percent, and/or sufficient patient satisfaction. These should be achieved after three to six treatments or after three to six months. In the absence of high-quality evidence in the burn population, our approach is as follows (table 2):

•For immature burn scar, minor burn keloid, or erythematous hypertrophic burn scar, we suggest intralesional injections with triamcinolone acetonide and silicone sheeting or gel as the first line of management (Grade 2C). Pressure dressings can be applied for approximately three weeks to limit progression. (See 'Immature scar, erythematous hypertrophic scar, minor keloid' above.)

•For widespread hypertrophic burn scars without associated tension, we suggest treatment with silicone sheeting or gel, or onion extract gel, and pressure therapy (Grade 2C). (See 'Widespread hypertrophic burn scar' above.)

•For widespread hypertrophic burn scars associated with tension that limit function or cause contractures, we suggest surgical scar release and scar excision/revision with adjunctive use of silicone sheeting or gel, or onion extract gel, and pressure therapy (Grade 2C). For patients who are not responsive to therapy, we use ablative fractional laser therapy. (See 'Widespread hypertrophic burn scar' above.)

•For major, refractory, or recurrent keloids, we suggest intralesional corticosteroids with adjuvant cryotherapy as a first-line strategy to reduce scar symptoms and volume (Grade 2C). If treatment is not effective, we use multimodality therapy, which includes intralesional fluorouracil and triamcinolone acetonide with spray cryotherapy, with or without pulsed-dye laser therapy. (See 'Refractory or recurrent major keloids' above.)