Early signs of melanoma are summarized by the mnemonic "ABCDEF":
Asymmetry
Borders (irregular with edges and corners)
Colour (variegated)
Diameter (greater than 6 mm (0.24 in), about the size of a pencil eraser)
Evolving over timeThis classification does not apply to nodular melanoma, which has its own classifications:
Elevated above the skin surface
Firm to the touch
GrowingMetastatic melanoma may cause nonspecific paraneoplastic symptoms, including loss of appetite, nausea, vomiting, and fatigue. Metastasis (spread) of early melanoma is possible, but relatively rare; less than a fifth of melanomas diagnosed early become metastatic. Brain metastases are particularly common in patients with metastatic melanoma. It can also spread to the liver, bones, abdomen, or distant lymph nodes. Cause
Melanomas are usually caused by DNA damage resulting from exposure to UV light from the sun. Genetics also play a role. Melanoma can also occur in skin areas with little sun exposure (i.e. mouth, soles of feet, palms of hands, genital areas). People with dysplastic nevus syndrome, also known as familial atypical multiple mole melanoma, are at increased risk for the development of melanoma.Having more than 50 moles indicates an increased risk melanoma might arise. A weakened immune system makes cancer development easier due to the bodys weakened ability to fight cancer cells. UV radiation
The UV radiation from tanning beds increases the risk of melanoma.
The International Agency for Research on Cancer finds that tanning beds are "carcinogenic to humans" and that people who begin using tanning devices before the age of thirty years are 75% more likely to develop melanoma.Those who work in airplanes also appear to have an increased risk, believed to be due to greater exposure to UV.UVB light (wavelengths between 315 and 280 nm) from the sun is absorbed by skin cell DNA and results in a type of direct DNA damage called cyclobutane pyrimidine dimers. Thymine, cytosine, or cytosine-thymine dimers are formed by the joining of two adjacent pyrimidine bases within a DNA strand. Somewhat similarly to UVB, UVA light (longer wavelengths between 400 and 315 nm) from the sun or from tanning beds can also be directly absorbed by skin DNA (at about 1/100 to 1/1000 of the efficiency of UVB).Exposure to radiation (UVA and UVB) is one of the major contributors to the development of melanoma. Occasional extreme sun exposure (resulting in "sunburn") is causally related to melanoma. Melanoma is most common on the back in men and on legs in women (areas of intermittent sun exposure). The risk appears to be strongly influenced by socioeconomic conditions rather than indoor versus outdoor occupations; it is more common in professional and administrative workers than unskilled workers. Other factors are mutations in or total loss of tumor suppressor genes.