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Asian Skin (asian + skin)
Selected AbstractsMinimally Ablative Erbium:YAG Laser Resurfacing of Facial Atrophic Acne Scars in Asian Skin: A Pilot StudyDERMATOLOGIC SURGERY, Issue 5 2008YONG-KWANG TAY MD BACKGROUND Atrophic scars are dermal depressions caused by collagen damage most commonly occurring after inflammatory acne vulgaris. There are little published data regarding the effectiveness and safety of minimally invasive lasers in the treatment of atrophic acne scars in darker skin types. OBJECTIVE The purpose was to evaluate the efficacy and safety of a low-fluence 2,940-nm erbium:YAG laser in the treatment of atrophic acne scars in Asian patients. MATERIALS AND METHODS Nine patients aged 19 to 45 years with mild to moderate atrophic facial scars and Skin Types IV and V were treated with topical anesthesia and one to two passes with an erbium:YAG laser two times at 1-month intervals. Treatment parameters were 6-mm spot size, fluence of 400 mJ, pulse duration of 300 ,s, and repetition rate of 2 Hz. RESULTS At 2 months after the last treatment, mild to moderate clinical improvement was noted in all patients compared to baseline. Treatment was well tolerated. Side effects consisted of posttreatment erythema, peeling, and crusting, which resolved within 1 to 2 weeks. There was no postinflammatory hyper- or hypopigmentation, blistering, or hypertrophic scarring. CONCLUSION Low-fluence erbium:YAG facial resurfacing was effective and safe in patients with mild to moderately severe atrophic acne scarring. [source] Nonablative 1450-nm Diode Laser in the Treatment of Facial Atrophic Acne Scars in Type IV to V Asian Skin: A Prospective Clinical StudyDERMATOLOGIC SURGERY, Issue 10 2004Sze-Hon Chua MRCP (UK) Background. There is presently little published data on the clinical effectiveness of nonablative lasers in the treatment of atrophic acne scars and the safety of their use in patients with darker skin types. Objective. This study aims to determine the clinical effectiveness and safety of the nonablative 1450 nm diode laser with cryogen cooling spray in the treatment of facial atrophic acne scars in Type IV-V Asian skin. Methods. This is a prospective non-comparative open study. 4 to 6 laser treatment sessions were performed on patients with atrophic acne scars. Final clinical assessment was performed 6 months after the last treatment. Results. 57 patients were evaluated. Patient's self-assessment of scar improvement as compared with doctor's assessment was as follows: patients who completed 4 treatments (15.7% vs 6.6%), patients who completed 5 treatments (20% vs 7.9%) and patients those who completed 6 treatments (17.3% vs 5.0%). Main side effects were mild to moderate pain during the procedure, transient erythema, and hyperpigmentation which occurred in 39% of treated patients. Conclusion. The nonablative 1450 nm diode laser may be effective in achieving mild to moderate gradual clinical improvement in the treatment of facial atrophic acne scars. The procedure is associated with minimal downtime and is safe for use in darker skin types IV and V. [source] Photorejuvenation for Asian Skin by Intense Pulsed LightDERMATOLOGIC SURGERY, Issue 7 2001Kei Negishi MD Background. Dermabrasion and deep chemical peeling are used in the treatment of photoaged skin. These ablative procedures are effective enough to produce a certain improvement but have often caused postinflammatory hyperpigmentation among Asian patients. To avoid such adverse effects, a new, nonablative procedure has been sought. Objective. To determine the effectiveness of photorejuvenation for Asian skin using intense pulsed light (IPL). The specific parameters used, improvement ratios, side-effects, and downtime required are also discussed. Methods. Ninety-seven patients were treated for photoaging using IPL. The cutoff filters of 550 nm and 570 nm were utilized for three to six treatments at intervals of 2 to 3 weeks. Results. Treatment results were evaluated and rated by both patients and physicians at the end of the third treatment based on improvement in pigmentation, telangiectasia, and skin texture. A combined rating of "good" or "excellent" was given to more than 90% of the patients for pigmentation, more than 83% for telangiectasia, and more than 65% for skin texture. There were some minor complications in four cases: one had erythema that continued to the next day and three had minor blisters leaving no marks. Conclusion. Photorejuvenation using IPL is a completely safe and effective procedure even for Asian skin. It will be increasingly used for skin rejuvenation in the future. [source] Photoepilation Results of Axillary Hair in Dark-Skinned Patients by IPL: A Comparison Between Different Wavelength and Pulse WidthDERMATOLOGIC SURGERY, Issue 2 2006JONG HEE LEE MD BACKGROUND Recently, intense pulsed light (IPL) sources have been shown to provide long-term hair removal. OBJECTIVE This study examined the photoepilatory effects of different wavelengths and pulse width application in the same device and compared their efficiencies in Asian skin. METHODS Twenty-eight Korean women were treated using HR (600,950 nm filter) and 27 using HR-D (645,950 nm filter) in the axillar area. Four treatments were carried out at intervals of 4 to 6 weeks; follow-ups were conducted 8 months after the last treatment. Mean energy settings were 14.9±2.0 J/cm2 for HR and 17.1±0.6 J/cm2 for HR-D. Longer pulse widths were applied in case of HR-D treatment. Hair counts and photographic evaluation of skin sites were made at baseline and at the last follow-up. Final overall evaluations were performed by patients and clinicians. RESULTS Average clearances of 52.8% and 83.4% were achieved by HR and HR-D, respectively. No significant adverse effects were reported after HR-D treatment. One case each of hypopigmentation and hyperpigmentation was reported for HR. CONCLUSION An IPL source by removing 45 nm of the emitted spectra and applying longer pulse width was found to provide a safer and more effective means of photoepilation in Asian patients. [source] Nonablative 1450-nm Diode Laser in the Treatment of Facial Atrophic Acne Scars in Type IV to V Asian Skin: A Prospective Clinical StudyDERMATOLOGIC SURGERY, Issue 10 2004Sze-Hon Chua MRCP (UK) Background. There is presently little published data on the clinical effectiveness of nonablative lasers in the treatment of atrophic acne scars and the safety of their use in patients with darker skin types. Objective. This study aims to determine the clinical effectiveness and safety of the nonablative 1450 nm diode laser with cryogen cooling spray in the treatment of facial atrophic acne scars in Type IV-V Asian skin. Methods. This is a prospective non-comparative open study. 4 to 6 laser treatment sessions were performed on patients with atrophic acne scars. Final clinical assessment was performed 6 months after the last treatment. Results. 57 patients were evaluated. Patient's self-assessment of scar improvement as compared with doctor's assessment was as follows: patients who completed 4 treatments (15.7% vs 6.6%), patients who completed 5 treatments (20% vs 7.9%) and patients those who completed 6 treatments (17.3% vs 5.0%). Main side effects were mild to moderate pain during the procedure, transient erythema, and hyperpigmentation which occurred in 39% of treated patients. Conclusion. The nonablative 1450 nm diode laser may be effective in achieving mild to moderate gradual clinical improvement in the treatment of facial atrophic acne scars. The procedure is associated with minimal downtime and is safe for use in darker skin types IV and V. [source] Photorejuvenation for Asian Skin by Intense Pulsed LightDERMATOLOGIC SURGERY, Issue 7 2001Kei Negishi MD Background. Dermabrasion and deep chemical peeling are used in the treatment of photoaged skin. These ablative procedures are effective enough to produce a certain improvement but have often caused postinflammatory hyperpigmentation among Asian patients. To avoid such adverse effects, a new, nonablative procedure has been sought. Objective. To determine the effectiveness of photorejuvenation for Asian skin using intense pulsed light (IPL). The specific parameters used, improvement ratios, side-effects, and downtime required are also discussed. Methods. Ninety-seven patients were treated for photoaging using IPL. The cutoff filters of 550 nm and 570 nm were utilized for three to six treatments at intervals of 2 to 3 weeks. Results. Treatment results were evaluated and rated by both patients and physicians at the end of the third treatment based on improvement in pigmentation, telangiectasia, and skin texture. A combined rating of "good" or "excellent" was given to more than 90% of the patients for pigmentation, more than 83% for telangiectasia, and more than 65% for skin texture. There were some minor complications in four cases: one had erythema that continued to the next day and three had minor blisters leaving no marks. Conclusion. Photorejuvenation using IPL is a completely safe and effective procedure even for Asian skin. It will be increasingly used for skin rejuvenation in the future. [source] Extramammary Paget's disease treated with topical imiquimod 5% creamDERMATOLOGIC THERAPY, Issue 4 2010Sue-Ann J. E. Ho ABSTRACT Extramammary Paget's disease (EMPD) is a rare cutaneous, intraepithelial adenocarcinoma usually found in the apocrine gland bearing areas. It is traditionally treated with surgery but has a high rate of recurrence. Of late, topical imiquimod 5% cream has come into use as another treatment option. We present two cases of EMPD in Asian skin treated successfully with topical imiquimod 5% cream. [source] Ethnic skin types: are there differences in skin structure and function?,INTERNATIONAL JOURNAL OF COSMETIC SCIENCE, Issue 2 2006A. V. Rawlings Synopsis People of skin of colour comprise the majority of the world's population and Asian subjects comprise more than half of the total population of the earth. Even so, the literature on the characteristics of the subjects with skin of colour is limited. Several groups over the past decades have attempted to decipher the underlying differences in skin structure and function in different ethnic skin types. However, most of these studies have been of small scale and in some studies interindividual differences in skin quality overwhelm any racial differences. There has been a recent call for more studies to address genetic together with phenotypic differences among different racial groups and in this respect several large-scale studies have been conducted recently. The most obvious ethnic skin difference relates to skin colour which is dominated by the presence of melanin. The photoprotection derived from this polymer influences the rate of the skin aging changes between the different racial groups. However, all racial groups are eventually subjected to the photoaging process. Generally Caucasians have an earlier onset and greater skin wrinkling and sagging signs than other skin types and in general increased pigmentary problems are seen in skin of colour although one large study reported that East Asians living in the U.S.A. had the least pigment spots. Induction of a hyperpigmentary response is thought to be through signaling by the protease-activated receptor-2 which together with its activating protease is increased in the epidermis of subjects with skin of colour. Changes in skin biophysical properties with age demonstrate that the more darkly pigmented subjects retaining younger skin properties compared with the more lightly pigmented groups. However, despite having a more compact stratum corneum (SC) there are conflicting reports on barrier function in these subjects. Nevertheless, upon a chemical or mechanical challenge the SC barrier function is reported to be stronger in subjects with darker skin despite having the reported lowest ceramide levels. One has to remember that barrier function relates to the total architecture of the SC and not just its lipid levels. Asian skin is reported to possess a similar basal transepidermal water loss (TEWL) to Caucasian skin and similar ceramide levels but upon mechanical challenge it has the weakest barrier function. Differences in intercellular cohesion are obviously apparent. In contrast reduced SC natural moisturizing factor levels have been reported compared with Caucasian and African American skin. These differences will contribute to differences in desquamation but few data are available. One recent study has shown reduced epidermal Cathepsin L2 levels in darker skin types which if also occurs in the SC could contribute to the known skin ashing problems these subjects experience. In very general terms as the desquamatory enzymes are extruded with the lamellar granules subjects with lowered SC lipid levels are expected to have lowered desquamatory enzyme levels. Increased pores size, sebum secretion and skin surface microflora occur in Negroid subjects. Equally increased mast cell granule size occurs in these subjects. The frequency of skin sensitivity is quite similar across different racial groups but the stimuli for its induction shows subtle differences. Nevertheless, several studies indicate that Asian skin maybe more sensitive to exogenous chemicals probably due to a thinner SC and higher eccrine gland density. In conclusion, we know more of the biophysical and somatosensory characteristics of ethnic skin types but clearly, there is still more to learn and especially about the inherent underlying biological differences in ethnic skin types. Résumé, Les gens qui ont une peau de couleur représentent la majorité de la population mondiale et les sujets asiatiques en représentent plus de la moitié. Pourtant la littérature consacrée aux caractéristiques de ces sujets est limitée. Plusieurs groupes de travail ont essayé au cours des dernières années de comprendre les différences sous-jacentes de la structure et de la fonction de la peau de différentes ethnies. Maisla plupart de ces études ont été réalisées à petite échelle et dans certains cas les différences observées entre les individus au niveau de la qualité de la peau ne font pas ressortir de différence entre races. Récemment, un besoin d'études reliant les diffèrences génétiques et phénotypiques entre différents groupes raciaux s'est fait sentir et de ce fait beaucoup d'études à grande èchelle ont été entreprises. La différence la plus évidente, entre les peaux ethniques, est leur couleur liée à la présence de la mélanine. La photoprotection induite par ce polymère influence le taux de vieillissement de la peau entre les différents groupes raciaux qui finalement sont tous sujets au processus de photovieillissement. Généralement, les caucasiens ont des signes plus précoces et plus importants de formation de rides et de relâchement de la peau; en général, les problèmes d'augmentation de la pigmentation sont observés sur les peaux de couleur, bien qu'une grande étude ait rapporté que des sujets originaires de l'Asie de l'Est vivant aux U.S.A. avaient le moins de taches pigmentaires. On pense que la réponse d'une induction hyperpigmentaire est due à un signal envoyé par le récepteur 2 activé par une protéase. Le récepteur 2 augmente en même temps que la protéase activatrice dans l'épiderme des sujets ayant une peau de couleur. Les changements dans les propriètés biophysiques de la peau en fonction de l'âge montrent que les sujets qui ont la pigmentation la plus sombre gardent une peau plus jeune par comparaison aux groupes qui possèdent une pigmentation moins forte. Toutefois, bien qu'ayant un stratum corneum plus compact, il existe des rapports divergents sur la fonction barrière de ces sujets. Dans le cas d'agression chimique ou mécanique, la fonction barrière du stratum corneum est considérée plus forte chez les sujets à peau plus foncée, malgré leurs taux plus faibles encéramide. On doit garder à l'esprit que la fonction barrière du stratum corneum dépend de toute son architecture et pas seulement de sa teneur en lipides. On considère que la peau asiatique à unePIE (TEWL) basale similaire à la peau caucasienne, ainsi que des taux en céramides comparables, mais on constate que dans le cas d'agression mécanique, elle possède un effet barrière le plus faible. Des différences dans la cohésion intercellulaire sont évidentes. A contrario, on a mis en évidence des taux d'hydratation (NMF) plus faibles dans son stratum corneum, comparativement à la peau caucasienne et afro-américaine. Ces différences expliquent les variations au niveau de la desquamation, mais on a très peu de données sur ce sujet. Une étude récente a mis en évidence des taux réduits de Cathepsin L2 dans l'épiderme des types de peau plus sombre, ce qui, si cela se produisait dans le stratum corneum, expliquerait les problèmes biens connus de cendrage de la peau que ces sujets connaissent. En terme très gènéral, étant donné que les enzymes liées à la desquamation sont libérées avec les granules lamellaires, on s'attend à ce que les sujets ayant des taux de lipides faibles dans le stratum corneum aient des taux d'enzymes liés à la desquamation faibles. On constate chez les sujets noirs une augmentation de la taille des pores, de la sécrétion du sébum et de la microflore cutanée. On observe également chez ces sujets une augmentation de la taille des granules mastocellulaires. Le phénomène de peau sensible se retrouve à une fréquence similaire dans les différents groupes raciaux, mais il existe des différences subtiles dans lesstimuli nécessaires pour l'induire. En tout cas, plusieurs études montrent que la peau asiatique est peut-être plus sensible aux produits chimiques exogènes, ce qui probablement est dûà un stratum corneum plus mince et à une densité de glandes eccrines plus élevées. En conclusion, c'est sur les caractéristiques biophysiques et somato-sensorielles des différents types de peaux ethniques que nous en savons plus, mais il est clair qu'il nous reste à comprendre encore beaucoup de choses principalement sur leurs différences biologiques. [source] Characteristics of skin aging in Korean men and womenINTERNATIONAL JOURNAL OF COSMETIC SCIENCE, Issue 1 2005J. H. Chung Introduction Korea is located between Japan and Mainland China. The people of these three countries have similar appearances and it is difficult to differentiate between them. Although the population of Asia is more than half of the total population of the Earth, the inherent characteristics of Asian skin have not been well investigated. Commercial markets for cosmetics and drugs for photoaged skin are rapidly expanding in many Asian countries. Therefore, many investigators in the field of dermatology and cosmetology have become interested in brown Asian skin. Clinical characteristics of skin aging and photoaging in Asians Skin aging can be divided into two basic processes: intrinsic aging and photoaging [1]. Intrinsic aging is characterized by smooth, dry, pale, and finely wrinkled skin, whereas photoaging, which indicates premature skin aging in chronically photodamaged skin, is characterized by severe wrinkling and irregular pigmentation. The pattern of wrinkling in Asians seems to differ from that in Caucasians. Asians have coarser, thicker and deep wrinkles, particularly in the forehead, perioral and Crow's foot areas. In contrast, Caucasians usually have relatively fine cheek and Crow's foot wrinkles. The reasons for these differences are not known and need further investigation. There are racial, ethnic and genetic differences, and differences of skin structure and function, between the brown skin of Asians and the white skin of Caucasians. As Asian skin is more pigmented, acute and chronic cutaneous responses to UV irradiation differ from those in white skin. Many people believe, based on clinical impressions, that the main process of photoaging in Asians involves pigmentary changes, rather than wrinkling. However, no study has been performed to confirm this belief. Risk factors for skin wrinkles and their relative risks in Korean skin [2] Various factors such as age, sun-exposure, and smoking are known to be important risk factors for wrinkles. However, the relative risks of each factor on wrinkles in the brown skin of Asians have not been investigated, and they could differ from those in Caucasians. An evaluation system for skin wrinkling is necessary for Asian skin [3]. Thus, we developed an eight-point photographic scale for assessing wrinkles in both Korean genders [2]. This scale can probably be applied to the populations of other Asian countries, at least to the Japanese and Chinese. The pattern of wrinkles in both genders appears to be similar. Age Age is an important risk factor for wrinkling in Asians, as in Caucasians. Korean subjects in their 60s showed a 12-fold increased risk of wrinkling, while subjects in their 70s have a 56-fold increased risk compared with young age group. UV light It is well known that the UV component in sunlight can cause and accelerate photoaging. The pigmented skin of Asian may better protect skin from acute and chronic UV damage. However, we found a strong association between sun-exposure and the development of wrinkling in Koreans. It was found that sun exposure of more than 5 h per day was associated with a 4.8-fold increased risk in wrinkling versus less than 2 h of sun-exposure in Koreans. Estrogen deficiency Korean females have more wrinkles than men, after controlling for age, sun exposure, and smoking, it was found that they have a 3.6-fold increased risk of developing wrinkles than their male counterparts [2]. It has also been reported, that the relative risk for wrinkling in women is higher than in men as for in white Caucasians [4]. The reason why women show more wrinkles remains to be determined. It is possible that a reduction in skin collagen because of estrogen deficiency in postmenopausal woman may aggravate wrinkling severity. Korean women with more than 10 years since menopause showed a 3.9-fold higher risk of wrinkling than the women 5 years of beyond menopause [5]. We demonstrated that women with a history of HRT have a significantly lower risk, more specifically, one fifth of the risk of facial wrinkling relative to those who had no history of HRT. Interestingly, we found that wrinkle severity significantly increased with an increasing number of full term pregnancies. The relative risk for severe wrinkling is increased by approximately 1.8-fold per full term pregnancy. Smoking It is known that smoking causes skin wrinkling in Caucasians, and that it plays no role in Blacks [6, 7]. Koreans with have a smoking history of more than 30 pack years showed a more than 2.8-fold increased risk of wrinkles [2]. The relative risks of wrinkles associated with a 30,50 pack-years history of smoking were 2.8- and 5.5-fold, respectively. Dyspigmentation in Asian skin To follow pigmentary changes, six photographic standards for both genders were developed for Korean skin, to produce a 6-point scale [2, 8]. Hyperpigmented spots, mostly lentigines, were prominent among women, while seborrheic keratosis tended to be more prominent in men. Seborrheic keratosis in Korean men Seborrheic keratoses (SKs) are benign cutaneous tumors. They have diverse clinical and histopathological appearances and are very common in the elderly (over 50 years old). The etiology of SKs is not well understood, although patients with a great number of lesionsshow a familial trait with an autosomal dominant pattern, and human papilloma virus has been suggested as possible cause because of verrucous appearance of the lesions. Exposure to sunlight has been suggested to be a risk factor for SKs. However, there is still some debate in terms of the role of sunlight. Recently, we have investigated the clinical characteristics of SKs and relationship between SKs and sunlight exposure in Korean males [9]. The prevalence of SKs in Koreans increases with age; it rose from 78.9% at 40 years, to 93.9% at 50 years and 98.7% in those over 60 years. Exposed areas, i.e. the face, neck and dorsum of the hands, demonstrate a significant increase in the prevalence of SKs by decade, whereas partly exposed areas, although SKs tended to increase in prevalence with age, this trend was not significant. When the estimated body surface area (BSA) is taken into account, the number of SKs on both the face and dorsum of the hands (0.51 ± 0.08 per 1% BSA) was over-represented compared with the trunk. SKs were also concentrated on the neck (0.38 ± 0.07 per 1% BSA) and in the V-area (0.47 ± 0.09 per 1% BSA). Outer forearms also showed 3-fold more SKs per unit area than neighboring arms and inner forearms, which are classified as partly exposed area (0.09 ± 0.02, 0.03 ± 0.01, respectively). The total area covered by SKs on exposed area also became significantly larger with aging than on intermittently exposed areas. These results indicate that exposure to sunlight might be related to SK growth. Our results indicated that excessive sun exposure is an independent risk factor of SKs. After controlling for age, smoking, and skin type, subjects with a sun exposure history of more than 6 hours per day showed a 2.28-fold increased risk of having severe SKs (n , 6) compared with those exposed for less that 3 h per day. These findings indicated that sun-exposure may play an important role in SK development. In summary, SKs are very common in Korean males and represent one of the major pigmentary problems. SKs concentrate on exposed skin, especially on the face and dorsum of the hands. Both age and lifetime cumulative sunlight exposure are important contributing factors and may work in a synergistic manner. Conclusion Many people tend to believe that wrinkles are not a prominent feature of Asian photoaged skin, and that dyspigmentation is a major manifestation in Asian skin. Contrary to this impression, wrinkling is also a major problem in the photoaged skin of Asians, and Korean people showing severe pigmentary changes usually tend to have severe wrinkles. In conclusion, the wrinkling patterns and pigmentary changes of photoaged skin in East Asians differ from those of Caucasians, and the relative risks of aggravating factors may be different from those of Caucasian skin. References 1.,Gilchrest, B.A. Skin aging and photoaging: an overview. J. Am. Acad. Dermatol. 21, 610,613 (1989). 2.,Chung, J.H. et al. Cutaneous photodamage in Koreans: influence of sex, sun exposure, smoking, and skin color. Arch. Dermatol. 137, 1043,1051 (2001). 3.,Griffiths, C.E. et al. A photonumeric scale for the assessment of cutaneous photodamage. Arch. Dermatol. 128, 347,351 (1992). 4.,Ernster, V.L. et al. Facial wrinkling in men and women, by smoking status. Am. J. Public Health. 85, 78,82 (1995). 5.,Youn, C.S. et al. Effect of pregnancy and menopause on facial wrinkling in women. Acta Derm. Venereol. 83, 419,424 (2003). 6.,Kadunce, D.P. et al. Cigarette smoking: risk factor for premature facial wrinkling. Ann. Intern. Med. 114, 840,844 (1991). 7.,Allen, H.B., Johnson, B.L. and Diamond, S.M. Smoker's wrinkles? JAMA. 225, 1067,1069 (1973). 8.,Chung, J.H. Photoaging in Asians. Photodermatol. Photoimmunol. Photomed. 19, 109,121 (2003). 9.,Kwon, O.S. et al. Seborrheic keratosis in the Korean males: causative role of sunlight. Photodermatol. Photoimmunol. Photomed. 19, 73,80 (2003). [source] Cutaneous malignant melanoma arising in an acquired naevus of OtaAUSTRALASIAN JOURNAL OF DERMATOLOGY, Issue 4 2009Clare RS Patterson ABSTRACT Naevus of Ota is a dermal melanocytosis most commonly found in black or Asian skin and is usually a benign malformation, but with a low risk of melanoma. We describe a 32-year-old Caucasian man with an acquired naevus of Ota with subtle pigmentation, in which a melanocytic papule developed. The lesion, deceptively, had no clinically suspicious features, but investigation revealed an aggressive cutaneous malignant melanoma, extensive orbital ring melanocytosis and metastatic brain and subsequent liver disease. [source] The patterns of melanosome distribution in keratinocytes of human skin as one determining factor of skin colourBRITISH JOURNAL OF DERMATOLOGY, Issue 3 2003H.-Y. Thong Summary Background One determining factor of skin colour is the distribution pattern of melanosomes within keratinocytes. Melanosomes in keratinocytes of light skin as in Caucasians are distributed as membrane-bound clusters, whereas the melanosomes in keratinocytes of dark skin as in African/American individuals tend to be larger and distributed individually. It has been shown that melanin content, melanin composition and the size of melanosomes in the human epidermis vary considerably with both ethnicity and chronic sun exposure. Objectives To assess quantitatively the distribution pattern of melanosomes that have been transferred to keratinocytes in the photoprotected (volar forearm) skin from normal Asian individuals and to compare these data with those from light-skinned Caucasian and dark-skinned African/American individuals. Methods Electron microscopy was used. Results We have demonstrated that melanosomes within keratinocytes of Asian skin are distributed as a combination of individual and clustered melanosomes with a proportion of 62·6% vs. 37·4%, respectively. This contrasts with dark and light skin keratinocytes where melanosomes are predominantly individual (88·9%) and clustered (84·5%), respectively. Analysis of mean ± SD melanosome size also revealed a progressive variation in size with ethnicity, melanosomes in dark skin being the largest (1·44 ± 0·67 ,m2 × 10,2) followed in turn by those in Asian skin (1·36 ± 0·15 ,m2 × 10,2) and Caucasian skin (0·94 ± 0·48 ,m2 × 10,2). In addition, it was shown that the melanosomes that are individually distributed tend to have a larger size than the clustered melanosomes. Conclusions The present data indicate that there may be a size gradient of melanosomes encompassing the global complexion coloration and that the melanosome distribution in keratinocytes of Asian skin is intermediate between that in light Caucasian and dark African/American skin. [source] |