A mole (or naevus) is the term applied to any spot on the skin. Many moles are coloured (pigmented) but some have no colour.
A melanoma is the medical term for a mole. This simply means any pigmented or non pigmented lesion; it does not mean a cancer. Although most moles are brown, they can vary from flesh coloured through yellow and blue, to black. Moles can be many different shapes and can be single or multiple, on almost any part of the body. Everybody has moles; some people have more than others. Most moles have formed before the age of 20, but some people can get new moles well into their 30s or beyond.
The vast majority of moles remain benign (non cancerous) and never cause any trouble. However, a small number may change with time and have the potential to become a cancerous mole (malignant melanoma). If a mole changes in size or colour, if it itches, is painful or bleeds, or if new nodules develop around it or it looks red and inflamed then the mole should be removed for examination.
It is important that moles are removed properly so they can be thoroughly examined. It is usually recommended that moles are removed with an ellipse of normal skin around them, aiming for a 2mm margin of clearance. Most of the moles that are removed turn out to be fine. Pathologists (doctors who examine tissues under the microscope) use different terms for benign moles. They may be junctional, juvenile, blue, compound, dermal or intradermal.
All these are descriptions for benign (non cancerous) moles. Some will be what are called dysplastic moles. These are thought to be precancerous moles that have the potential to become malignant melanomas if they are left. Although many of them may not turn cancerous it is impossible to tell and so they should probably be removed.
The next stage after the dysplastic mole is the malignant melanoma in situ. This has just turned cancerous, but does not have the ability to spread. Like the dysplastic mole, it is cured by removing it properly. Malignant melanomas proper have the ability to spread around the body, so the earlier they are caught the better.
It seems that the most important factor in determining whether a malignant melanoma may have spread or not is its thickness. This is measured in mm and is called the Breslow thickness. Depending on the thickness, a wider removal of the skin around a malignant melanoma is usually recommended. Malignant melanomas that are less than 1mm thick have a greater than 95% chance of causing no further trouble.
Another way of measuring the thickness of a malignant melanoma is the Clarke’s level. This relates to which layers of the skin the malignant melanoma has penetrated. This is less accurate that the Breslow thickness in predicting the likelihood of further problems.
As with other cancers, it is important that people who have had malignant melanomas are treated by a team of specialists. Melanoma specialists include a dermatologist, a surgeon and perhaps a plastic surgeon, an oncologist and a pthologist.
Some groups of people should be regularly checked for abnormal moles. These include people who have had a malignant melanoma before, or there is a family history of it, fair skinned, fair haired or red haired people and those with a large number of moles or previous dysplastic moles, as well as those who have had considerable sun exposure in their lives, particularly with episodes of severe sunburn when they were young.
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