The cause is not clearly understood, but is thought to be caused by a defect in embryologic development. This is in the first twelve weeks of pregnancy. The defect is thought to cause a proliferation of melanocytes. This means melanocytes, the cells in the body in charge of normal<unk>  color, are being produced at an extremely fast rate, thus causing the melanocytes to form in clusters instead of spread out, causing abnormal<unk>  pigmentation in some areas of the body. Genetics Genes can have an influence on a person's moles. Dysplastic nevus syndrome is a largely hereditary condition which causes a person to have a large quantity of moles (often 100 or more) with some larger than normal or atypical. This often leads to a higher risk of melanoma, a serious<unk><unk> . Dysplastic nevi are more likely than ordinary moles to become<unk> ous. Dysplastic nevi are common, and many people have a few of these abnormal moles. Having more than 50 ordinary moles increases the risk of developing melanoma. In the overall population, a slight majority of melanomas do not form in an existing mole, but rather create a new growth on the<unk> . Somewhat surprisingly, this also applies to those with dysplastic nevi. They are at a higher risk of melanoma occurring not only where there is an existing mole, but also where there are none. Such persons need to be checked regularly for any changes in their moles and to note any new ones. Sunlight Ultraviolet light from the sun causes premature aging of the<unk>  and<unk>  damage that can lead to melanoma. Some scientists hypothesize that overexposure to UV, including excessive sunlight, may play a role in the formation of acquired moles. However, more research is needed to determine the complex interaction between genetic makeup and overall exposure to ultraviolet light. Some strong indications that this is so (but falling short of proof), are: *The relative lack of moles on the buttocks of people with dysplastic nevi. *Freckles (spots of melanin on the<unk> , and distinct from moles) are known to be influenced by sunlight. Studies have found that sunburns and too much time in the sun can increase the risk factors for melanoma. This is in addition to those who have dysplastic nevi being at higher risk of this<unk>  (the uncertainty is in regard to acquiring benign moles). To prevent and reduce the risk of melanoma caused by UV radiation, the American Academy of Dermatology and the National<unk>  Institute recommends staying out of the sun between 10 a.m. and 4 p.m. standard time (or whenever one's shadow is shorter than one's height). The National<unk>  Institute also recommends wearing long sleeves and trousers, hats with a wide brim, sunscreens, and sunglasses that have UV-deflecting lenses.
symptom of Skin cancer
symptom of Psoriasis
symptom of Melanoma
symptom of Basal-cell carcinoma
symptoms of Keratoconus
symptom of Keratoconus
symptom of Herpes labialis
symptom of Alopecia areata