Moles and Melanoma

A potentially fatal melanoma.Although most moles are benign, some can form cancerous growths. Precancerous or cancerous moles can develop into melanoma, a rare and often deadly form of skin cancer. Both moles and melanoma have a hereditary aspect: if a person has a family history of moles, they are likely to develop moles, much like a family history of cancer elevates a person's risk of developing cancer. A family history of melanoma is a crucial risk factor, elevating a person's risk of developing melanoma by a factor of ten or more. It is important to know what kinds of moles to monitor carefully and what characteristics of a mole make it readily become cancerous in order to minimize one's risk of developing mole-related skin cancers.

The tendency to develop moles is most influenced by heredity. How readily a person will develop moles is influenced by how readily their parents and other relatives develop moles. Most benign moles appear before a person is twenty years of age. Moles that are present at birth are significantly more likely to develop into a cancerous mole than moles that appear after birth, and when the child is ready to begin visiting medical specialists, it may be beneficial to have a dermatologist evaluate and track any changes in such moles. Many people have between ten and forty moles by the time they reach adulthood; this is considered a relatively normal number of moles, although a person may have more moles than this and never develop a mole-related medical condition. The number of moles is not as important when evaluating cancer risk as the qualities of the moles themselves.

Although most moles a person develops in the first twenty years of their life are benign, it is important to watch all moles, particularly moles that are elevated from the skin, for changes in their appearance. Moles occur when specialized skin cells called melanocytes grow in clusters. Melanocytes are responsible for giving skin its color; melanocytes produce a brownish pigment called melanin that is normally not noticeable when spread throughout the skin normally, but when they grow together and release their pigments, they form moles that are noticeably darker than the surrounding skin. Cancerous growths are caused by unchecked cellular growth. A mole that continues to change may be undergoing unchecked growth and needs to be evaluated by a dermatologist as soon as possible. Since melanoma readily metastasizes, early detection and treatment can lead to a more optimistic prognosis than a patient would otherwise have by waiting longer to see a specialist.

There are three types of skin cancers that are related to moles. Melanoma is the one that causes the most concern, since it is the deadliest form of skin cancer. Although it is the rarest form of skin cancer, it causes seventy-five percent of skin cancer-related deaths. The reason melanoma is so problematic is that it readily metastasizes, meaning that it easily spreads from the skin to other organ systems. In addition to readily spreading, it can also go undetected because melanoma tends to form in the middle part of the body and the legs, where a person may not be able to see them. It also tends to form in moles that already exist as opposed to forming a new mole, which the other types of skin cancer related to moles often do. Thus, a mole that a person already knows about on her back may change in color or texture, but she may not notice it since it is in a place that is not readily visible to her.

Signs of Melanoma

Knowing the signs to look for when evaluating moles at home for melanoma can help spot a melanoma while it is still in the in-situ stage, the earliest stage of development. This is when the melanoma cells are still only in the surface layers of the skin and unable to spread to other organ systems; this is the least harmful stage of melanoma when treatment is least difficult and most effective.

Dermatologists recommend a system called the ABCD or ABCDE system. Each letter refers to a different characteristic of the mole that a person should evaluate.

  • A refers to asymmetry: asymmetrical lesions or moles that are asymmetrical are considered abnormal.
  • B refers to the border of the mole: moles with ragged, irregular borders as opposed to smooth, rounded borders can often develop into melanoma, particularly if the border of the mole changes.
  • C refers to color. Moles that are cancerous often have several colors that are different shades of brown, tan and black.
  • D refers to the diameter of the mole. Moles that are more than six millimeters in diameter are considered at risk for developing into melanoma; however, many melanomas have a diameter that is smaller than six millimeters, so this aspect of the system is considered ineffective, and even if a mole that shows one or more of the other characteristics in the system does not have a diameter larger than six millimeters, it should be evaluated by a dermatologist anyway.
  • The E component of the system may or may not be present, depending on the literature a patient consults. It can either refer to the elevation or evolution of a mole. Increased elevation of a mole is what often leads a patient to consult a doctor, but not all melanomas are elevated from the skin. Evolution simply refers to any changes in the mole's appearance or texture.

Changes in the mole are often the most reliable indicator of melanomas, and many physicians now recommend simply monitoring moles for changes, whether or not the changes are strictly part of the ABCDE system. Some software applications for tracking changes in moles are available and may be a helpful tool for evaluating one's moles.

Continually evaluating one's risk for melanoma or other mole-related skin cancers should be an integral part of one's at-home cancer screening. Self-exams are the most important prevention tool a patient can have for several different types of cancer. Knowing one's risk for developing melanoma by considering both family history and individual risk factors can enable one to be proactive in cancer prevention and early detection. The Mayo Clinic's melanoma website has more information about symptoms of melanoma.