INTRODUCTION
Ultraviolet (UV) irradiation of the skin leads to acute inflammatory reactions such as erythema, sunburn, and chronic reactions, including premature skin aging and skin tumors. Photoaging is a complex and chronic process that induces structural and functional changes in sun-exposed skin, including coarse wrinkles, laxity, dyschromia, telangiectasias, and potential precancerous lesions. UV irradiation (both UVB and UVA) is a potent generator of oxidative stress in the skin, increasing the cellular levels of reactive oxygen species, which damages lipids, proteins, and nucleic acids in both epidermal and dermal cells, and contributes to the sunburn reaction as well as photo carcinogenesis and photoaging.1All skin types do not react to UV irradiation in the same way. Pigmented skin (Fitzpatrick skin type III-IV) presents different structure and physiology that contribute to distinctive photoaging process. The increased amount of melanin in pigmented skin provides some protection from photodamage and photoaging among skin or color populations and lowers the risk of skin cancer. Skin of color subjects generally have fewer visible signs of aging (deep wrinkles, fine lines, rough surface texture, and sun spots). However, darker skin tones are more sensitive to UV, visible light, and infrared-induced skin pigmentation. Their skin is more susceptible to certain skin conditions including post-inflammatory hyperpigmentation (may occur after injury, burn, cut, etc.), melasma, pityriasis alba (round, light patches covered with fine scales), dry or “ashy” skin, dermatosis papulosa nigra, and at greater risk of keloid development.2 The incidence of skin cancer among U.S. Hispanics has also increased 1.3 % annually from 1992 to 2008.The Hispanic population is projected to be among the fastest growing population in the United States. They are projected to increase from 55 million in 2014 to 119 million in 2060, an increase of 115% and by 2060, 29% of the U.S. is projected to be Hispanic-- more than one-quarter of the total population.3 Hispanic-Americans come from a wide range of geographical areas, which may differ in their specific cultural, ethnic, and national characteristics. The Hispanic group in the U.S. includes people with Puerto Rican, Dominican, Cuban, Venezuelan, Mexican, or other Latin American origins or mixed populations. This diversity may contribute to a wide range of skin complexions with different hues and undertones that make proper clinical skin assessment for photoaging or pathological conditions more complex.4
Clinical and Instrumental Assessment of Skin Color
When performing clinical evaluation of skin complexion or color shift under physiological or pathological conditions, multiple methodologies have been adopted to help define and track the progression. Traditional Fitzpatrick assessment of skin phototypes is important for understanding the photo-reactivity of skin, however, it does not correlate well with skin tone, especially when color shifts occur due to photo aging or diseased conditions. Vissher et al demonstrated the use of individual typology angle (ITA) values determined from L* and b* values, where 6 groups of skin pigmentation were classified: ITA greater than 55 (very light tone), 41 to 55 (light tone), 28 to 41 (intermediate tone), 10 to 28 (tan), -30 to 10 (brown), and less than-30 (dark tone).5 The ITA values and categories correlated well with skin melanin content based on mexameter measure
