TRICHLOROACETIC ACID (TCA) has a particularly long history as an effective agent for rendering histologic and clinical improvement to the skin and is particularly safe when used as a superficial peel or in "combination peels" of medium depth for acne scars.
Application of TCA to the skin causes precipitation of proteins and coagulative necrosis of cells in the epidermis and necrosis of collagen in the papillary to upper reticular dermis.1 Over several days the necrotic layers slough and the skin reepithelializes from the adnexal structures that were spared from chemical damage.3
Dermal collagen remodeling after chemical peel may continue for several months.
Many investigators have observed that the clinical effects of TCA were due to both a reorganization in dermal structural elements and an increase in dermal volume as a result of an increase in collagen content, glycosaminoglycan, and elastin.
Recent studies have shown that the reticular dermis heals with scarring. They offer an explanation for some of the increased risk associated with the use of TCA for deeper peels, suggesting that peeling with higher TCA concentrations is very risky and definitely not recommended.8 We also have limited experience and very little information regarding the effects of higher TCA concentrations for acne scars in dark complexioned patients, including Koreans (types IVVI), whose skin is known to develop post inflammatory hyper pigmentation.
In order to maximize the effects of TCA and to overcome complications such as scarring, hyper pigmentation, and hypopigmentation, we suggest a technique consisting of the focal application of higher TCA concentrations by pressing hard on the entire depressed area of atrophic acne scars using a sharpened wooden applicator (Figure 1).
Eventually it produces multiple, frosted white spots on each acne scar (Figure 2). This technique is called chemical reconstruction of skin scars (CROSS) by the authors; however, the technique itself has not been patented or restricted to prevent usage. The CROSS method, achieved with 65% or 100% TCA alone, has the advantage of reconstructing acne scars by focusing on the dermal thickening and collagen production that increase with high TCA concentrations.
Healing is more rapid and has a lower complication rate than conventional full-face medium to deep chemical resurfacing, because the adjacent normal tissue and adnexal structures are spared. This technique does not involve the classic full-face chemical resurfacing, but rather it can be used on focal chemical scar reconstruction.
We have used this technique successfully for treating facial acne scars and dilated pores for the past 10 years. The purpose of this study was to evaluate the clinical effects of the CROSS method on atrophic acne scars in dark-complexioned patients.
Materials and Methods
An analysis was conducted of 65 patients with atrophic acne scars who were treated with the CROSS method in our hospitals between July 1996 and July 2001. The CROSS method consists of the focal application of higher TCA concentrations by pressing hard on the entire depressed area of atrophic acne scars using a sharpened wooden applicator (Figure 1). TCA, 65-100% weight/volume, unbuffered, was made to order by a local pharmacy.
The patients' ages ranged from 25 to 45 years (mean 32.5 years). Fifty-five patients were women and 10 were men. All patients had Fitzpatrick skin types IV-V. Thirty three patients were treated with 65% TCA CROSS and 32 with 100% TCA CROSS.
For independent clinical assessment, two blinded physicians evaluated the photographs taken before treatment and 6 months after completion of the treatment. Physicians categorized the improvement as follows: excellent, improvement greater than 70%; good, improvement of 50-70%; fair, improvement of 30-50%; poor, improvement less than 30%.
The patient satisfaction rates were recorded from the interviews conducted 6 months after the last treatment.
The physicians evaluated complications such as persistent erythema, permanent hyperpigmentation, hypopigmentation, herpes simplex flare-up, scarring, or keloids.
Patients were evaluated carefully before treatment about the factors considered important, including the patients' current and past medications and active acne lesion. Relevant history was obtained, including any history of prior hypertrophic scarring, keloids, allergies, or herpes simplex infection. Before CROSS, pretreatments such as tretinoin cream were not applied because of the risk of unpredictable and excessive TCA penetration.
After facial washing with soap, the skin was cleansed with alcohol. And then either 65% TCA or 100% TCA was focally applied by pressing hard on the entire depressed area of atrophic acne scars using a sharpened wooden applicator (Figure 1). The skin was monitored carefully until it reached a "frosted" appearance after a single application.
The frosted appearance is the result of coagulation of epidermal and dermal proteins and is used mainly to monitor the peel depth. Focal application of TCA produced even frosted spots on each acne scar within 10 seconds (Figure 2).
After CROSS, an ointment based antibiotic instead of an occlusive dressing was applied for moisturizing effect, but this application was discontinued after crust formation in order to avoid the risk of detaching the crust. Oral prophylaxis consisting of antibiotics and antiviral medications were not needed after CROSS. One to 2 weeks after CROSS, a moisturizer sunscreen cream consisting of 0.05% tretinoin, 5% hydroquinone, and a hydro base was used in some patients for a minimum of 4 weeks.
The application of makeup was allowed after CROSS. CROSS was repeatedly performed every 1-3 months to allow dermal thickening and collagen production.
Local anesthetics or sedation were not needed for CROSS. Patients were comfortable during the procedure.
Results:
The patient treatment data indicated that 27 of 33 patients (82%) (the 65% TCA group) and 30 of 32 patients (94%) (the 100% TCA group) experienced a good clinical response (Table 1). In the 65% TCA group, 15 of 15 patients (100%) who received more than six courses of treatment demonstrated good or excellent results, as did 2 of 5 patients (40%) who received treatment three times (Table 1 and Figure 3).
Of interest is that all patients in the 100% TCA group who received five or six courses of treatment showed excellent results (Table 1 and Figure 4). Table 1 shows that the clinical effects of 100% TCA CROSS were better than those of 65% TCA CROSS.
Good satisfaction rates in the 65% and 100% TCA groups were recorded in 27 of 33 patients (82%) and 30 of 32 patients (94%), respectively (Table 2). In the 65% TCA group, 16 of 33 patients (49%) and 11 of 33 patients (33 %) were satisfied with this therapy absolutely and moderately, respectively (Table 2). In the 100% TCA group, 19 of 32 patients (59%) and 11 of 34 patients (34%) were satisfied absolutely and moderately, respectively (Table 2).
There were no cases of significant complication at the treatment sites such as persistent erythema, permanent hyperpigmentation, hypopigmentation, herpes simplex flare-up, scarring, or keloids. Relative to the 65% TCA CROSS treatment, 100% TCA CROSS did not increase the frequency of complications. Only mild erythema, which faded over 2-8 weeks, and transient post inflammatory hyperpigmentation, which disappeared over 6 weeks, occurred. Mild pustular eruptions occurred in only four patients and cleared within 1 week with the use of cefadroxil500 mg three times a day.
The two patients who received isotretinoin for 3 months before treatment showed good results without excessive scarring, although it should be noted that full-face medium to deep chemical resurfacing is relatively contraindicated in patients who have taken isotretinoin within the previous 6 months because of the increased risk of hypertrophic scarring.
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