Freckle

Freckle
Classification and external resources

Facial freckles on a child.
ICD-10 L81.2
MeSH D008548

Freckles are clusters of concentrated melanin which are most often visible on people with a fair complexion. A freckle is also called an "ephelis".

Contents

Biology

Freckles can be found on anyone no matter their genetic background; however, having freckles is genetic and is related to the presence of the dominant melanocortin-1 receptor MC1R gene variant.[1] 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.

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.

Extremely freckled women.

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 however fade with age in some cases.

Freckles are not a skin disorder. People with freckles usually have a lower concentration of photoprotective melanin and are therefore more susceptible to the harmful effects of UV-radiation. An overexposure of UV-radiation should be avoided. Sunscreen has been suggested.[2][3]

Types of freckles

Freckles on a woman's arm.

Ephelides is a genetic trait. It is used to describe a freckle which is flat, light brown or red, and fades in the winter. 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. Lentigines are more common in older people.

See also

References

  1. ↑ Online 'Mendelian Inheritance in Man' (OMIM) 266300
  2. ↑ 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. 
  3. ↑ 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. PMID 1546792. http://www.ajph.org/cgi/reprint/82/4/614. 

External links

Pigmentation disorders/Dyschromia (L80-L81, 709.0)
Hypo-
Vitiligo
(loss of melanocytes)
Quadrichrome vitiligo · Vitiligo ponctué · syndromic (Alezzandrini syndrome · Vogt–Koyanagi–Harada syndrome)
Albinism
(loss of melanin)

Oculocutaneous albinism · Ocular albinism · syndromic (Hermansky–Pudlak syndrome · Chédiak–Higashi syndrome · Griscelli syndrome (Elejalde syndrome · Griscelli syndrome type 2 · Griscelli syndrome type 3) · Waardenburg syndrome · Tietz syndrome  · Cross–McKusick–Breen syndrome · ABCD syndrome · Albinism–deafness syndrome)

hypomelanosis (Idiopathic guttate hypomelanosis · Phylloid hypomelanosis · Progressive macular hypomelanosis)
Ungrouped
ungrouped: Piebaldism · Nevus depigmentosus · Postinflammatory hypopigmentation · Leukoderma · Pityriasis alba · Vagabond's leukomelanoderma · Yemenite deaf-blind hypopigmentation syndrome · Wende–Bauckus syndrome · Woronoff's ring · Amelanism · Leucism
Hyper-
Melanin/
Melanosis/
Melanism

Lentigo (Lentigo simplex, Liver spot, Generalized lentiginosis) · Acanthosis nigricans (Acral acanthotic anomaly) · Melasma · Freckle · Café au lait spot · Riehl melanosis

Dermatopathia pigmentosa reticularis · Dyschromatosis symmetrica hereditaria · Dyschromatosis universalis hereditaria · Familial progressive hyperpigmentation · Galli–Galli disease · Pallister–Killian syndrome · Periorbital hyperpigmentation · Photoleukomelanodermatitis of Kobori · Pigmentatio reticularis faciei et colli · Poikiloderma (Poikiloderma of Civatte · Poikiloderma vasculare atrophicans) · Postinflammatory hyperpigmentation · Reticular pigmented anomaly of the flexures · Reticulate acropigmentation of Kitamura · Revesz syndrome · Scratch dermatitis · Vasospastic macule · X-linked reticulate pigmentary disorder · Transient neonatal pustular melanosis
Other
pigments

iron: Hemochromatosis · Iron metallic discoloration · Pigmented purpuric dermatosis (Schamberg disease, Majocchi's disease, Gougerot–Blum syndrome, Doucas and Kapetanakis pigmented purpura/Eczematid-like purpura of Doucas and Kapetanakis, Lichen aureus, Angioma serpiginosum) · Hemosiderin hyperpigmentation

other metals: Argyria · Chrysiasis · Arsenic poisoning · Lead poisoning · Titanium metallic discoloration

other: Carotenosis · Tattoo · Tar melanosis · Shiitake mushroom dermatitis

: INT, SF, LCT

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