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出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2013/07/23 12:48:51」(JST)

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For other uses, see freckles (disambiguation).

Freckles are clusters of concentrated melanin which are most often visible on people with a fair complexion. A freckle is also called an ephelis. Freckles do not have an increased number of melanin producing cells (melanocytes). This is in contrast to lentigines and moles.^[1]

Biology[edit]

Freckled women. Freckles cover the face, chest and shoulders.

Freckles can be found on anyone no matter their genetic background; however, the amount of freckles is genetic and is related to the presence of the melanocortin-1 receptor MC1R gene variant.^[2] The formation of freckles is triggered by exposure to sunlight. The exposure to UV-B radiation activates melanocytes to increase melanin production, which can cause freckles to become darker and more visible.

Freckles are predominantly found on the face, although they may appear on any skin exposed to the sun, such as the shoulders. Freckles are rare on infants, and more commonly found on children before puberty. Upon exposure to the sun, freckles will reappear if they have been altered with creams or lasers and not protected from the sun, but do fade with age in some cases. Their intensity can be altered with citric acid. Freckles are not a skin disorder, but people with freckles generally have a lower concentration of photoprotective melanin and are therefore more susceptible to the harmful effects of UV-radiation. It is suggested that they avoid overexposure and use sunscreen.^[3]^[4]

Types of freckles[edit]

Freckles on the arm

Ephelides describes a freckle which is flat and light brown or red and fades with reduction of sun exposure. Ephelides are more common in those with light complexions, although they are found on people with a variety of skin tones. The regular use of sunblock can inhibit their development.

Liver spots (also known as sun spots and lentigines) are freckles that may not fade in the winter. Rather, they form after years of exposure to the sun. Liver spots are more common in older people.

References[edit]

Notes

^ Robbins and Cotran Pathologic Basis of Disease Elsevier. 2005. Page 1232. ISBN 0-8089-2302-1 .
^ Online 'Mendelian Inheritance in Man' (OMIM) Skin/Hair/Eye Pigmentation, variation in, 2; SHEP2 -266300
^ Hanson Kerry M.; Gratton Enrico; Bardeen Christopher J. (2006). "Sunscreen enhancement of UV-induced reactive oxygen species in the skin". Free Radical Biology and Medicine 41 (8): 1205–12. doi:10.1016/j.freeradbiomed.2006.06.011. PMID 17015167.
^ Garland C, Garland F, Gorham E (1992). "Could sunscreens increase melanoma risk?". Am J Public Health 82 (4): 614–5. doi:10.2105/AJPH.82.4.614. PMC 1694089. PMID 1546792.

Bibliography

Millington GWM (2006). "Proopiomelanocortin (POMC): the cutaneous roles of its melanocortin products and receptors". Clin Exp Dermatol 31 (3): 407–412. doi:10.1111/j.1365-2230.2006.02128.x. PMID 16681590.

External links[edit]

Wikimedia Commons has media related to: Freckles

MedicineNet.com: Freckles
Ephelides (Freckles) at eMedicine

UpToDate Contents

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1. 色素沈着過剰を有する患者へのアプローチ approach to the patient with hyperpigmentation disorders
2. 皮膚色素過剰症に対するレーザーおよび光線療法 laser and light therapy for cutaneous hyperpigmentation
3. ポイツ・イェガース症候群：疫学、臨床症状、および診断 peutz jeghers syndrome epidemiology clinical manifestations and diagnosis
4. 色素細胞性母斑（ほくろ）以外の良性色素性皮膚病変 benign pigmented skin lesions other than melanocytic nevi moles
5. 色素沈着不全 the dyschromatoses

English Journal

Effect of cinnamaldehyde on melanosis and spoilage of Pacific white shrimp (Litopenaeus vannamei) during storage.

Mu H, Chen H, Fang X, Mao J, Gao H.SourceFood Science Institute, Zhejiang Academy of Agricultural Sciences, Hangzhou 310021, China.
Journal of the science of food and agriculture.J Sci Food Agric.2012 Aug 15;92(10):2177-82. doi: 10.1002/jsfa.5605. Epub 2012 Jan 30.
BACKGROUND: Shrimp is a very perishable product and postmortem changes occur rapidly. Sulfiting agents were once and are still widely used as a preservative in the shrimp industry. However, the application of sulfite in shrimp may pose a risk to human health. Thus development of a natural preservati
PMID 22290525

Withania somnifera extract attenuates stem cell factor-stimulated pigmentation in human epidermal equivalents through interruption of ERK phosphorylation within melanocytes.

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Journal of natural medicines.J Nat Med.2012 Jul;66(3):435-46. Epub 2011 Nov 16.
We previously demonstrated that mitogen-activated protein kinase (MAPK) signaling, including microphthalmia-associated transcription factor (MITF) and cAMP response element-binding protein (CREB) phosphorylation, is a major pathway involved in up-regulating melanogenesis within human melanocytes in
PMID 22086674

Japanese Journal

Protection and Therapy of Photoaging

ANTI-AGING MEDICINE 8(6), 88-91, 2011
… We demonstrated clinical effectiveness of an IPL source for solar lentigines and ephelides on the face with well tolerability. … Moreover, we showed clinical effects of a novel IPL source on solar lentigines and ephelides. …
NAID 130001290313

皮膚トラブルの原因と対策(第3回)しみとそばかす

本好捷宏
コスメティックステージ 4(2), 43-46, 2009-12
NAID 40016949922

トラネキサム酸配合乳液の肝斑・雀卵斑に対する使用成績

近藤慈夫,岡田裕子,富田靖
皮膚の科学 6(3), 309-315, 2007
しみ・そばかすに対するトラネキサム酸配合乳液の外用による有用性を肝斑25例，雀卵斑8例に5週から18週間使用させて調べた。最終観察時では，肝斑に対しては20例(80%)，雀卵斑に対しては6例(75%)に良好な成績が得られた。また，副作用は認められず，トラネキサム酸の安全度に問題はなかった。皮膚所見の推移をみると，肝斑では8週以内に試験乳液の効果が認められ，雀卵斑では12週以内に試験乳液の効果が約6 …
NAID 130004547253