RX OF HYPERTROPHIC SCAR AND KELOIDS
For centuries, keloids and hypertrophic scars have been recognized as abnormal responses to trauma. Although morphologic differences between these two entities have been acknowledged for years, discovery of a histopathologic distinction is more recent.
The keloid is defined as an abnormal scar that grows beyond the boundaries of the original site of skin injury. Keloids have the clinical appearance of a raised amorphous growth, and are frequently associated with pruritus and pain. Scanning electron microscopy reveals a number of distinguishing features, including randomly organized collagen fibers in a dense connective tissue matrix. In normal scars, the collagen bundles are arranged parallel to the skin surface, as in the third image below.
The treatment of keloids can be subdivided into surgical, nonsurgical, and combined modality treatment. Many published reports advocate a variety of therapies; however, few studies provide a coherent therapeutic plan because of poorly defined endpoints in treatment, inadequate follow-up care, failure to properly distinguish between hypertrophic scars and keloids, and lack of prospective studies. Most of the literature on keloids suggests that a high recurrence rate (50%) is expected, regardless of treatment.
If located in an amenable anatomic location, hypertrophic scars can generally be treated with simple excision, providing wound closure can occur without undue tension. Steroid injections may be appropriate, depending on the particular wound and the patient. Although an injection of intralesional triamcinolone acetate usually flattens the raised scar and decreases pruritus, the discolored or atrophic appearance of the widened portion of the scar remains.
Limitations of steroid treatment must be recognized by the surgeon and the patient to optimize satisfaction with the results. Steroid injections must be administered cautiously to avoid overtreatment, which may result in skin atrophy, telangiectasias, and a depressed scar. In general, scar revision with an excision and atraumatic closure and with possible reorientation of the scar by using W-plasties or Z-plasties can usually improve widened hypertrophic scars. This procedure provides a narrower scar, decreases the tension along the scar, and improves scar camouflage.
The bulk of the remaining discussion focuses on various treatment methods for keloids.
Surgical and ablative treatment of keloids
Keloids treated with simple excision have a recurrence rate ranging from 50-80%. The use of Z-plasties or any wound-lengthening technique for excising keloids is strongly discouraged. Complete excision and near-total excision (ie, leaving behind a small remnant of keloid on the peripheral portions of the incision) have both been advocated. The theoretical benefit of the latter is that previously uninjured tissue is not traumatized, decreasing the chances of recurrence; however, whether the residual keloid remnant contributes to further keloid development remains unclear. Wide undermining should be used to make closure of these wounds tension-free. Provided that adjacent tissue is manipulated, wide undermining may or may not increase the risk of keloid recurrence.
The use of cuticular, monofilament, synthetic permanent sutures is advised to decrease tissue reaction. Tissue adhesives may provide a less reactive skin closure, which may decrease the likelihood of keloid formation. Further studies are necessary to evaluate this hypothesis.
Lasers, such as carbon dioxide, pulse dye, neodymium-yttrium aluminum garnet (Nd-YAG), and argon, have been used as alternatives to cold excision for keloids; however, the use of lasers is expensive and cumbersome. Superiority of laser use to simple excision currently has not been demonstrated in clinical trials. Further research and technologic developments may enhance the effectiveness of lasers to treat keloids in the future.
Cryosurgery is a form of ablative modality proposed by certain authors. Zoubolis et al reported a good or excellent response in 61% and poor or no response in 39% of keloid study participants (n=55).The mechanism of action of cryotherapy involves the use of a refrigerant to induce a frostbite-type injury with cellular damage and vascular sludging. The period required to achieve a response is significant, 2-10 sessions separated by 25 days. One of the main adverse effects is hypopigmentation due to injury to melanocytes in the basal layer of the epidermis. A randomized study by Mourad et al indicated that intralesional cryotherapy for keloids is more effective and requires fewer treatments than does spray cryotherapy. The study included 50 patients, with a 6-month follow-up.
Nonsurgical treatment of keloids
The application of mechanical pressure by compression devices is advocated in the treatment of keloids. Pressure may theoretically break up collagen bundles and soften the keloid mass; however, therapy must be instituted for long periods (>23 h/d for 6 mo) before significant effect can be achieved. Unfortunately, many regions of the head and neck are not amenable to pressure application. Silicone sheeting is used to decrease the irritation and pruritus associated with keloids. The proposed mechanism of action involves maintenance of scar hydration and inducement of a subsequent decrease in cytokine release, resulting in less collagen deposition. Certain authors report great success in keloid regression with this modality. Unfortunately, the general opinion on silicone sheeting does not support significant reduction in the dimensions or pigment characteristics of keloids, although silicone sheeting can be very effective in decreasing pruritus.
Various therapies, including nitrogen mustard, tetroquinone, antihistamines, retinoic acids, zinc, vitamin A, vitamin E, and verapamil, have been used with varying degrees of success.
Interferon (IFN) therapy is used because of its ability to reduce collagen synthesis in dermal fibroblasts. Granstein et al reported a 30% reduction in keloid height after intralesional injections of IFN-gamma 3 times weekly for 3 weeks. As with other treatment modalities, some recurrences are to be expected. IFN has untoward adverse effects, including low-grade fevers, a flulike illness for 48-72 hours after injection, and pain on injection.
Combined modality treatment of keloids
One of the most commonly used combination therapies employs cold-knife excision followed by postoperative injection of intralesional steroid. The injection into the lesion typically occurs 2-3 weeks postoperatively, followed by repeat injection in 3-4 weeks. Preoperative or intraoperative steroid injection may delay wound healing and increase the possibility of wound dehiscence. The most commonly used form of steroid is triamcinolone suspension; however, dexamethasone and cortisone can also be used. A concentration of 10 mg/mL of triamcinolone is used as the starting point and can be increased to as high as 40 mg/mL for denser, more recalcitrant keloids. The lower dose is preferred because of the potential complications of intralesional steroids, including depigmentation and dermal atrophy. The literature, confirmed by clinical experience, reports a negligible incidence of systemic effects.
The mechanism of action of corticosteroids is inhibition of fibroblast growth and promotion of collagen degradation. Surgical excision followed by postoperative intralesional steroid injection is reported by some authors to have recurrence rates as low as 50%, while other authors report recurrence rates as high as 70%.
A combination of surgical excision and external beam radiotherapy is implemented in certain centers. Radiation therapy adversely affects fibroblast growth and collagen production. Sclafani et al conducted a randomized prospective trial comparing keloid excision followed by intralesional steroid injection with keloid excision followed by radiotherapy.Results of the study did not demonstrate statistical significance but were able to show a trend toward a lower recurrence rate in the radiated group. The typical dosing range for external beam radiotherapy is 700-1500 cGy administered within 1 week of excisional surgery. A second method of radiation therapy involves the use of interstitial iridium 192 high-dose-rate brachytherapy. Some authors report that the immediate timing of radiation therapy may actually improve patient compliance.
A study by De Cicco et al indicated that in patients with keloids, low-dose-rate and high-dose-rate postoperative brachytherapy are associated with similar recurrence rates but that patients who receive high-dose-rate treatment have a greater incidence of symptom relief. In the study, recurrence rates for low-dose-rate (38 patients, 46 keloids) and high-dose-rate (39 patients, 50 keloids) brachytherapy were 30.4% and 38%, respectively. However, pain, itching, or stress, present at diagnosis in 64 keloids, was relieved in 92% of patients who received high-dose-rate brachytherapy but in just 68% of those who underwent low-dose-rate treatment.
The disadvantages of treating a benign process with radiation include the potential of inducing thyroid or salivary gland neoplasia, which has a latency period of 15-20 years. Shielding techniques are used to safeguard against such occurrences but should not be considered foolproof. In areas where the surrounding normal structures can be adequately shielded (eg, the earlobes), radiation therapy is a reasonable and viable option.