الفهرس 
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Abstract
Keloids and hypertrophic scars are dermal fibro proliferative disorders that usually develop after healing of a skin injury, although keloids sometimes occur spontaneously. Clinically, Keloids initially manifest as raised erythematous lesions that become pale as they age, extending beyond the original wound borders, do not usually regress spontaneously and tend to recur after excision. On the other hand, hypertrophic scars are raised erythematous fibrous lesions that remain within the confines of the original wound and usually undergo partial spontaneous resolution with time. In addition to the clinical differences between keloids and hypertrophic scars, each has unique histological appearance. Keloids are characterized by haphazard deposition of thick, hyalinized eosinophilic collagen bundles within the dermis with abundant mucinous mucopolysaccharide ground substance. The collagen bundles form nodules that contain an abundance of eosinophils, mast cells, plasma cells and lymphocytes. Hypertrophic scars also demonstrate increased collagen bundles but are less clearly demarcated and lack the hyalinized appearance noted with keloids. Moreover, they remain parallel to the epithelial surface as observed with normal skin. In addition, hypertrophic scars show myofibroblasts with α smooth muscle actin expression believed to be important in the pathogenesis of contractures. The aetiopathogenesis of keloids and hypertrophic scars is not completely understood. Predisposing factors include trauma, skin tension, foreign body, infection, immunological factors, hormonal factors, hypoxia and genetic predisposition. These result in increased fibroblasts proliferation; responsible for enhanced collagen production and excessive scarring. Keloids and hypertrophic scars represent a major therapeutic dilemma to the dermatologists. As enhanced collagen production represents the main frame for the pathogenesis of both conditions, the various treatment methods aim at breakage or removal of the overformed collagen. These methods include surgical, non- surgical as well as combined treatments. Surgical treatment includes surgical excision, cryotherapy and laser treatment. Non- surgical treatment includes intralesional steroid, radiation therapy, silicone gel sheeting and pharmacological treatment. Combined treatment represents combination of intralesional steroid with surgery, cryotherapy or laser treatment. BTXA could be used in controlling hypertrophic scars due to the temporary denervation of BTXA. As we all know, tension is one of the chief factors determining the degree of scar formation. Use of ablative fractional lasers (AFLs), such as CO2 or Erbium: yttrium aluminum garnet (Er:YAG) fractional lasers, for the treatment of hypertrophic scar. It was supposed that tissue penetration leads to remodeling and production of new collagen. When compared to CO2, Er:YAG produces columns with a narrower rim of thermal coagulation due to its higher affinity for absorption by water which leads to more ablation than coagulation. In our study, We aimed to compare the efficacy between combined fractional Er:YAG with intra-lesional botulinum toxin (Botox) and intra-lesional Botox as a monotherapy for the treatment of HTS and keloids. Thirty patients with HTS and keloids were treated by intra-lesional injection of Botulinum Toxin Type –A (Botox) as a monotherapy and Botox combined with ablative fractional Er:YAG laser. Each lesion was divided into two parts. The allocation of treatment method was randomly selected. One part was treated with Botox intra-lesionally 5 IU/cm2. The other part was subjected to combined intra-lesional Botox and ablative fractional Er:YAG laser (2,940 nm) sessions (4 sessions every 4 weeks). Evaluation of the treatment outcomes was done by the Vancouver Scar Scale (VSS), clinical imaging, and immuno-histochemical studies. There was a significant decline in VSS after treatment with the combined regimen compared to the sites treated with botox injection only (P<0.001). Additionally, there was a highly significant difference between the combined treated sides and the Botox monotherapy sides in both the epidermal thickness (P=0.001) and area% hypodermis (P=0.001). In conclusion treatment of HTS and keloids with the combined approach of Er:YAG and Botox is more effective than Botox alone.