Freckles

From Wikipedia, the free encyclopedia

(Redirected from Freckle)

For other uses, see Freckles (disambiguation).

Freckles on a child.

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

1 Biology
2 Types of freckles
3 References
4 See also
5 External links

[edit] Biology

Extremely freckled women. Predisposition to freckles is genetic and is related to the presence of the MC1R gene variant.

Freckles can be found on anyone no matter the 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 the melanin production, which causes freckles to become darker.

Freckles are predominantly found on the face, although they may appear on any skin exposed to the sun. Freckles are rare on infants, and more common on children before puberty; they are less common on adults.

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] ^[4]

[edit] Types of freckles

Ephelides is a genetic trait. It’s used to describe a freckle that is flat, light brown or red, and fades in the winter. Ephelides are more common in those with light complexions (although are found on people with a variety of skin tones) and with the regular use of sunblock, can be suppressed.

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

[edit] References

^ Online 'Mendelian Inheritance in Man' (OMIM) 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. PMID 1546792, http://www.ajph.org/cgi/reprint/82/4/614.
^ Sunscreens and Cancer by Hans R Larsen

[edit] See also

Wikimedia Commons has media related to:

Freckles

[edit] External links

http://www.medicinenet.com/freckles/article.htm

v • d • e

Diseases of the skin and appendages by morphology

Growths

Epidermal	verruca, clavus, seborrheic keratosis, acrochordon, molluscum contagiosum, actinic keratosis, squamous cell carcinoma, basal cell carcinoma, merkel cell carcinoma, nevus sebaceous, trichoepithelioma

Pigmented	ephelis, lentigo, melasma, nevus, malignant melanoma

Dermal and subcutaneous	epidermal inclusion cyst, hemangioma, dermatofibroma, keloid, lipoma, neurofibroma, xanthoma, Kaposi's sarcoma, infantile digital fibromatosis, granular cell tumor, leiomyoma, lymphangioma circumscriptum, myxoid cyst

Rashes

With epidermal involvement

Eczematous	essential dermatitis, contact dermatitis, atopic dermatitis, seborrheic dermatitis, stasis dermatitis, lichen simplex chronicus, Darier's disease, glucagonoma syndrome, langerhans cell histiocytosis, lichen sclerosus, pemphigus foliaceus, Wiskott-Aldrich syndrome, Zinc deficiency

Scaling	psoriasis, tinea corporis, tinea cruris, tinea pedis, tinea manuum, tinea faciale, pityriasis rosea, secondary syphillis, mycosis fungoides, systemic lupus erythematosus, pityriasis rubra pilaris, parapsoriasis, icthyosis

Blistering	herpes simplex, herpes zoster, varicella, bullous impetigo, acute contact dermatitis, pemphigus vulgaris, bullous pemphigoid, dermatitis herpetiformis, porphyria cutanea tarda, epidermolysis bullosa simplex

Papular	scabies, insect bite reactions, lichen planus, miliaria, keratosis pilaris, lichen spinulosus, transient acantholytic dermatosis, lichen nitidus, pityriasis lichenoides et varioliformis acuta

Pustular	acne vulgaris, acne rosacea, folliculitis, impetigo, candidiasis, gonococcemia, dermatophyte, coccidioidomycosis, subcorneal pustular dermatosis

Hypopigmented	tinea versicolor, vitiligo, pityriasis alba, postinflammatory hypopigmentation, tuberous sclerosis, idiopathic guttate hypomelanosis, leprosy, hypopigmented mycosis fungoides

Without epidermal involvement

Red

Blanchable Erythema

Generalized	drug eruptions, viral exanthems, toxic erythema, systemic lupus erythematosus

Localized	cellulitis, abscess, furuncle, erythema nodosum, carcinoid syndrome, carcinoma erysipeloides, fixed drug eruption

Specialized	urticaria, erythema multiforme, erythema migrans, erythema gyratum repens, erythema annulare centrifugum, erythema ab igne

Nonblanchable Purpura

Macular	thrombocytopenic purpura, actinic purpura

Papular	disseminated intravascular coagulation, vasculitis

Indurated

scleroderma/morphea, granuloma annulare, lichen sclerosis et atrophicus, necrobiosis lipoidica

Miscellaneous

Featured MP3 :

Freckle - Related Items

Freckle

Freckle - In the news

© 2008 Netencyclo - Netencyclo Home - Terms of Service - Privacy Policy - Program Policies
Netencyclo, the Wikipedia mirror : the biggest multilingual free-content encyclopedia on the Internet. It uses material from the Wikipedia article Freckle. All Wikipedia content is licensed under the GNU Free Documentation License (see details). Content on this web site is provided for informational purposes only. We accept no responsibility for any loss, injury or inconvenience sustained by any person resulting from information published on this site. We encourage you to verify any critical information with the relevant authorities.

- Freckle -