406 JOURNAL OF COSMETIC SCIENCE Following the pulsed-dye laser, solid state, synthetic crystal lasers such as the ruby, alexandrite and Nd:YAG lasers were developed. These lasers are mainly used for the treatment of pigmented lesions such as: tattoos, freckles and lentigos, and pigmented birthmarks like Cafe au Lait macules and Nevus of Ota and Ito. These lasers have very short pulse durations in the nanosecond domain. Longer pulse duration Nd:YAG lasers using a KTP doubling crystal to increase the frequency and half the wavelength from 1064 nm to 532 nm have been developed for treating linear veins that occur commonly on the face and legs. The next major innovation in laser development were lasers to selectively remove hair by stimulating an inflammatory response causing a prolonged telogen phase of hair growth. These lasers used relatively long pulse durations in the millisecond domain, and long wavelengths not absorbed by hemoglobin that could penetrate to reach the entire hair shaft. In addition, these lasers use large spot sizes for increased depth of penetration. The innovations in facial rejuvenation have been the broadest. Radiofrequency, infrared lasers including diode lasers, intense pulsed light sources (IPLs) and numerous other devices emitting electromagnetic radiation have been used to rejuvenate and tighten skin. In addition, lasers have developed to target fat to reduce cellulite and possibly dissolve fat without the need for liposuction. The recent explosion in laser development reflects society's increasing age and its increasing desire to hide its advancing age. Topical products play a pivotal role in augmenting lasers' effects, as well as in reducing the likelihood of temporary and permanent side-effects. Lasers that ablate the skin surface such as the erbium or carbon dioxide lasers used for skin resurfacing, or the q-switched lasers used for removal of tattoos or pigmented lesions require both pre- and post-treatment to minimize the risk of post-treatment hyperpigmentation and scarring. Permanent hypopigmentation is a late side-effect of these lasers that is still poorly understood. Even non-ablative laser treatments such as laser hair removal, vascular lesion removal, or non-ablative rejuvenation benefit from intelligent use of topicals pre- and post­ treatment. Carefully considered topical treatment regiments can reduce side effects and augment the benefits of laser treatments.

2006 ANNUAL SCIENTIFIC SEMINAR 407 SPECIAL CONSIDERATIONS IN THE TREATMENT OF ETHNIC SKIN Andrew F. Alexis, M.D. Department of Dermatology, St. Luke)s-Roosevelt Hospital, 1090 Amsterdam Avenue, # l lB, New Yhrk, NY 10025 andrew.a!exis@columbia.edu Introduction: Ethnic skin or "skin of color" refers to the broad range of skin types and complexions that characterize individuals of African, Asian, Latino, and Middle Eastern descent. Differences in structure, function, and cultural practices in individuals with ethnic skin contribute to variations in the prevalence and clinical presentation of numerous skin conditions. Understanding these differences is paramount in the treatment of ethnic skin, especially in the context of cosmetic skin care. In particular, numerous cosmetic procedures can be associated with disfiguring complications when the nuances of treating pigmented skin are not taken into consideration. These complications include, but are not limited to, dyspigmentation, keloid scarring, and thermal injury. Special considerations in the performance of chemical peels, laser treatment, and cosmetic surgery will be discussed. Moreover, differences in cosmetic needs and concerns in ethnic skin populations will be addressed. Structural and Functional Differences: A number of structural differences between darkly pigmented skin and fair (Caucasian) skin have been reported. Most notably, skin of color is characterized as having increased epidermal melanin (produced by melanocytes), which is packaged within melanosomes that are larger, more numerous, and more dispersed throughout the epidermis. 1 In addition, the rate of degradation of melanosomes is slower in darkly pigmented skin. 2 Other reported structural differences include, an increased number of cell layers in the stratum corneum, increased stratum corneum lipid content, and larger, more numerous fibroblasts in the dermis. These structural features have a number of functional implications. First, skin of color is less susceptible to photodamage from ultraviolet (UV) light compared to Caucasian skin given the protective effect of melanin. Second, labile melanocyte responses to injury or inflammation often lead to dyspigmentation in ethnic skin, such as postinflammatory hyper- and hypo- pigmentation. Third, dermal injury is associated with a greater risk of keloids or hypertrophic scarring as a result of fibroblast reactivity. Racial differences in the structure of the hair follicle and hair shaft include the presence of curved hair follicles and spiral shaped hair shafts in blacks. On cross-section, African or "black" hair is elliptical whereas Asian hair is round, while Caucasian hair is intermediate. 3 These differences in hair structure may contribute (at least in part) to the increased prevalence of certain hair and scalp disorders in African­ Americans such as pseudofolliculitis barbae, acne keloidalis nuchae, and dissecting cellulitis. Treatment Considerations: The above structural and functional characteristics have numerous implications in the treatment of ethnic skin. In particular, procedures that induce epidermal or dermal injury should be performed with caution to minimize the risk of dyspigmentation and hypertrophic scarring or keloid formation. Therefore, resurfacing procedures, such as chemical peeling and microdermabrasion should be superficial in nature (limited to the epidermis and superficial papillary dermis). Moreover, concomitant therapies that may increase the depth of resurfacing, such as topical retinoids, should be restricted these agents are typically discontinued at least 1 week before a resurfacing procedure. Despite these limitations, both chemical peels (using salicylic acid and glycolic acid) and microdermabrasion, can be performed safely in darkly pigmented skin.45 While photodamage and wrinkles are leading indications for resurfacing procedures in light skinned individuals, postinflamrnatory hyperpigmentation, acne, and melasma are the most common reasons for which chemical peels are performed in dark skinned ethnic groups (in the author's experience).