Fractional Erbuim-YAG laser combined with Botulinum toxina versus botulinum toxina alone for treatment of hypertrophic scars and keloids / Seif Allah Mohamed Refaat Elfiky ; Supervised Hisham Shokeir , Nevien Samy

Thesis (Ph.D.) - Cairo University - National Institute of Laser Enhanced Sciences - Department of Laser Applications in Medical and Biological

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 Ü smooth muscle actin expression believed to be important in the pathogenesis of contractures

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