الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
Melasma is a human melanogenesis dysfunction. It is a common acquired condition manifested as symmetrical hyperpigmentation, most commonly on the face in three predominant patterns: Centro facial, malar and mandibular. Most melasma cases occur in females with darker skin types (Fitzpatrick skin types III to V). Still all ages, races and skin color may be affected. The most common causes of melasma include exposure to ultraviolet radiation, genetic influences, pregnancy, oral contraceptives, thyroid diseases, cosmetics, and phototoxic drugs. Melasma is classified into three main types: epidermal, dermal, and mixed. The epidermal type is the most common in which melanin is distributed throughout the epidermis. In the dermal type, the pigmentation due to plenty of melanophages in the dermis. In the mixed type, the pigmentation is due to increased epidermal melanin as well as dermal melanophages. Determining the type of melasma is of diagnostic and prognostic value. It is well known that epidermal melasma responds better to treatment than dermal melasma. Several therapeutic modalities are being used to treat melasma, which include numerous topical agents, chemical peels, dermabrasion, and a variety of lasers and light-based devices. A range of different lasers had been tried in the treatment of melasma including full-face resurfacing using CO 2 or erbium YAG laser, a variety of fractional ablative and non-ablative lasers, intense pulsed light (IPL), and q-A range of different lasers had been tried in the treatment of melasma including full-face resurfacing using CO 2 or erbium YAG laser, a variety of fractional ablative and non-ablative lasers, intense pulsed light (IPL), and q-switched Nd:YAG laser (QSL) which emits 1064 nm wave length and pulse duration with nanosecond. The aim of this study was to assess, both clinically and histopathologically, the efficacy of low fluence 1,064 Q-switched Nd:YAG laser in treatment of melasma. This study included 20 female patients with different types and patterns of melasma, diagnosed by typical appearance of skin lesions and confirmed by Wood’s light and dermoscopic examinations. The patients were selected from those attending the Outpatient Clinic of Dermatology and Venereology Department, Tanta University Hospitals during the period between February, 2018 and June, 2019. The patients had been treated with Q-switched Nd:YAG for five sessions, at two weeks interval, with 6mm spot size, 3.0J/cm2 and 10 HZ frequency. Biopsy was taken from ten patients before and after treatment for histopathological assessment of Q-switched Nd:YAG laser in melasma treatment. At the end of treatment period, ten cases showed excellent improvement (50%), six patients showed marked improvement (30%), three patients showed moderate improvement (15%) and one patient showed mild improvement (5%).