Asian Skin

Many Asians residing in the Far East are exposed to sunlight year round and are therefore very susceptible to photodamage and accompanying photoaging. Several studies of Asian populations demonstrate pigmentary changes as a major component of photoaging.These include facial hyperpigmentation, solar lentigines, and pigmented seborrheic keratoses (Fig. 3.3). In a study by Goh, the characteristics of photoaging in an Asian population in Singapore, which consisted of Chinese, Indonesians, and Malaysians, was described [26]. The population consisted of 1,500 subjects with skin types III and IV. In this population, hyperpigmentation was noted to be an early and prominent feature of photodamage. In contrast, coarse and fine wrinkling were found to be late and inconspicuous features of photoaging.

Characteristics of cutaneous photodamage in another Asian population consisting of 407 Korean men and women ages 30–92 years were investigated by Chung [27]. Chung identified wrinkling and dyspigmentation as the primary characteristics of photoaging in that population. Figure 3.4 is an example of both dyspigmentation and wrinkling in an Asian woman. In this study, the number of wrinkles increased as the age of the individual increased. This was the case as well for dyspigmentation. In the Korean population, dyspigmentation appeared as two distinct types of lesions: hyperpigmented macules on sun-exposed skin were described, as well as pigmented seborrheic keratoses. The number of pigmentary lesions increased as the age of the individual increased. Gender differences in the type of pigmentary lesions were also noted. In Koreans greater than 60 years of age, seborrheic keratoses were more common in men than in women. In those 50 years of age and older, hyperpigmented macules were found more frequently in women than in men. Women in the fourth decade had an average of 4.3 hyperpigmented macules, which increased to 23.5 by the sixth decade and 25.1 by the eighth decade.Men in the fourth decade had an average of 0.1 seborrheic keratoses,which increased to 4.6 by the sixth decade and 13.6 by the eighth decade.

Additionally, Chung established the association between sun exposure and the development of wrinkling in the Korean population [27]. Previously, wrinkling was not felt to be a major feature of photoaging in Asian populations. Chung demonstrated wrinkling in 19.2% of Koreans with a daily exposure of 1–2 h compared with 64.6% of those who had more than 5 h/day. Sun exposure of more than 5 h/day was associated with a 4.8-fold increased risk for wrinkling compared with 1–2 h/day. The pattern of wrinkling in both sexes was similar, but there was a greater risk for development of wrinkles in women than in men after controlling for age, sun exposure, and smoking. In this study,with regard to both wrinkles and dyspigmentation, increased severity became apparent at 50 years of age, and there was a statistically significant association between wrinkling grades and dyspigmentation grades. The effect of excessive sun exposure and cigarette smoking on wrinkling was found to be multiplicative in this Korean population. Sun exposure of more that 5 h/day and a smoking history of more than 30 pack-years (when controlled for age and gender) were associated with a 4.2-fold increased risk for wrinkling compared with a 2.2-fold increase for nonsmokers with 1–2 h/ day of sun exposure. There was, however, no significant association observed between smoking and dyspigmentation.

Known reported the prevalence of pigmented seborrheic keratoses in 303 Korean males ages 40–70 years [28]. Seborrheic keratoses occurred on sun-exposed areas of the skin, with the majority of lesions concentrated on the face and the dorsa of the hands. Similar to Chung’s report, the prevalence of seborrheic keratoses in Kwon’s study was shown to increase by age, with 78.9% of Korean men having seborrheic keratoses at age 40, 93.9% at age 50, and 98.7% at 60 and older. The mean overall prevalence of seborrheic keratoses in was 88.1%. Both chronological aging and cumulative sun exposure were independent variables for the development of seborrheic keratoses. Those Koreans with a lifetime cumulative sun exposure of more than 6 h/day had two times the risk of developing seborrheic dermatoses than those with less than 3 h/day. In summary, in Asian skin, in addition to wrinkling, hyperpigmented macules, solar lentigines, and seborrheic keratoses were the major pigmentary alterations as demonstrated in several studies.