Treatment of keloids (K) and hypertrophic scars (HTS) is challenging. A few case reports reported good results in HTS treated by fractional CO2 laser. The aim of the present study was the assessment of the clinical response as well as histological changes in K and HTS treated by fractional CO2 laser and the role of matrix metalloproteinase 9 (MMP9) in the response. A randomized half of the scar was treated by fractional CO2 laser in 30 patients (18 K, 12 HTS) for a total of four sessions 6 weeks apart. Vancouver scar score (VSS) was done before and 1, 3, and 6 months after the last laser session by a blinded observer. Biopsies taken from normal skin, untreated scar, and treated scar tissue 1 and 3 months after the laser sessions were stained by HX & E for histological changes and Masson trichrome for collagen fiber arrangement. Immunohistochemical staining for MMP9 was done in before and 1 month after samples. Quantitative morphometric analysis was done for collagen and MMP9 by image analyzer. Nineteen patients completed the 6-month follow-up period (12 K, 7 HTS). VSS score was significantly lower in the treated compared to untreated areas after 3 and 6 months in both K and HTS but was mainly due to improved pliability of the scar. Histologically, dense inflammatory infiltrate and increased vascularity was apparent 1 month after laser sessions and disappeared at 3 months. Thinner better organized collagen bundle could be seen in 3 months after samples. MMP9 was significantly increased in after treatment samples but without significant correlation with VSS. Fractional CO2 resurfacing is safe but affects mainly pliability of K and HTS with collagen remodeling apparent 3 months after therapy. MMP9 may play a role in mechanism of action of CO2 laser in K and HTS.

NB UVB 311 nm has similar repigmentary effects as PUVA. The addition of psoralen does not increase its efficacy.

SummaryBackground Chemical peels and topical depigmenting agents have become a popular modality in the treatment of melasma. Aims To compare the clinical efficacy of trichloroacetic acid peel 20% vs. Jessner's solution peel vs. the topical mixture of hydroquinone 2% and kojic acid. Patients and methods Forty five patients with melasma were randomly assigned into three groups of fifteen patients each. Group A received Jessner's solution peel, group B received trichloroacetic acid peel 20%, and group C received topical hydroquinone 2% and kojic acid. All patients were seen in follow-up period after 16 weeks; clinical evaluation using Melasma Area and Severity Index (MASI) score and photography were recorded before and after treatment and after 16 weeks. Results There was a decrease in MASI score in all three groups after treatment and after follow-up period but after treatment MASI score was statistically significantly lower in group A than group C (P = 0.01), and it was also statistically significantly lower in group B than group C (P < 0.001) but there was no statistically significant difference between groups A and B. After the follow-up period, MASI score was statistically significantly lower in group A than group C (P < 0.001), statistically significantly lower in group B than group C (P < 0.001), and statistically significantly lower in group B than group A (P = 0.035). The statistical analysis was done through one-way anova followed by least significant difference (LSD). Conclusion Trichloroacetic acid 20% showed better results than Jessner's solution as peeling agent and hydroquinone 2% with kojic acid as a topical agent in the treatment of melasma.

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