What Are Moles?
Benign skin growths, such as moles, are very common and virtually everyone has some form of them. "Benign" means the growth is not cancerous. Some of these growths have genetic origins, and for some, the cause is not clear.
These skin growths may appear as flat "stains" in the skin or as raised clusters made up of tiny blood vessels, small irregularities that can be a variety of shapes or colors, flaps of skin attached on only one side, or dark, fibrous scar tissue. Most skin changes are benign, but any unusual or suspicious skin growth should be checked by a medical provider. The growth can be removed if it is unsightly, interferes with clothing, or proves to be malignant (cancerous).
If you have many moles that you are worried about, you can go see your primary care doctor to follow the moles. However, treatment is only considered if a new mole develops or changes.
Common skin changes
As a person ages, more changes may appear in the skin. However, moles generally appear within the first six months of life and peak in the 20s. Common types of skin changes are:
- Birthmarks: These may appear as flat "stains" in the skin or as raised clusters made up of tiny blood vessels.
- Moles: These are small irregularities that originate in the pigment-producing cells in the skin. They can be almost any shape or color but are normally no larger than one-quarter inch across.
- Skin tags: These are little irregular flaps of skin, like a flattened mole attached on only one side.
- Keloids: This is a dark, fibrous form of scar tissue that forms after a skin wound, either from trauma or from surgery.
Moles are collections of melanin that change the color of skin locally. The "spot" that is formed by a mole can have a particular size and shape.
- Flat moles: This is a typical mole, sometimes referred to as junctional nevi.
- Slightly raised moles: This type is referred to as a compound mole.
- Rubbery textured moles: Intradermal nevi rarely occur.
- Painless moles: Usually moles do not hurt, they do not bleed, and they grow very slowly if at all.
- Benign moles: Usually the only symptom of a benign mole is its appearance which is stable over the life course.
A raised mole (e.g. intradermal nevi) is a benign (non-cancerous) growth that usually appears on fair-skinned people and is most commonly pink or reddish in coloration. There are many other types of raised or rubbery growths that can affect the skin including seborrheic keratoses. If you are experiencing a new, raised bump, it may need medical evaluation.
Development of malignancy/cancer
While it is rare for a mole to become cancerous, it happens with enough frequency that regular evaluations of a mole over the lifespan are important. Identifying cancerous changes early is an important way to promote proper treatment of a mole. The common criteria for development of a mole are described by the mnemonic "A-B-C-D-E," or :
- Evolving size
There are cells under the skin called "nevus cells" that exist in bunches. Nevus cells are one of the cell types that can produce melanin in the skin. The distribution and ability of these cells to produce melanin determine whether a mole will form under the skin. There is no single cause for the formation of a mole. Moles, instead, are caused by multiple factors causing a local increase in the amount of melanin under the skin.
One of the primary factors in the development of acquired melanocytic nevi are genetics. Many genes impact the formation of skin, and a change in a particular gene that is passed down can contribute to the formation of moles . Genes can trigger a mole to form without any additional factors, however, these moles are often congenital (occur at birth). More commonly, a gene may cause a mole to form over time when triggered by an event such as aging, puberty, or sun exposure. A gene may predispose nevi to begin to release larger amounts of melanin after it has received a certain type of stimuli.
Generally speaking, what we recognize as moles are more common in individuals with larger amounts of nevus cells and lightly pigmented skin. In practice, small studies found that the number of nevi in adolescents identified as "white" was six times higher than that found among non-white races . However, individuals with light skin and fair hair paradoxically tend to have fewer nevi than those with dark hair.
Exposure to sunlight can trigger moles in individuals that are genetically predisposed. Sunlight can trigger cells to increase melanin production to protect the structures within the body from the harmful effects of UV radiation. It should be noted, that over time, exposure to sunlight or genetic predisposition in combination with an exposure to sunlight can lead to atypical moles which are a major risk factor for skin cancer . Risk factors for developing melanoma from moles include unusual appearance or recent changes in the appearance of a mole .
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Treatment Options and Prevention for Moles
Moles are common skin changes and are commonly benign. However, if you have a new or existing skin change or mole that is concerning, you should consult your physician.
Most moles or nevi do not develop malignancy throughout the lifespan. However, for individuals with many moles, the risk of developing a malignancy is higher. The risk of malignancy is dependent on the amount of moles present. Skin cancer is much more treatable if it is caught early in its development. Individuals with many moles or individuals with fair skin and a predisposition for skin cancer are should be evaluated for skin cancer regularly.
Avoid UV radiation
Proper application of sunscreen and the use of a proper strength of sunscreen are important to preventing benign moles and even normal skin from developing into skin cancer. It is important to apply sunscreen with adequate SPF (sun protection factor). SPF 15 is adequate to protect from 95 percent of harmful rays. SPF 30 is sufficient to protect from 99.5 percent of harmful rays. Additionally, wearing clothing to reduce exposed skin or wearing a hat can help protect skin from radiation that may cause skin cancer.
It is important to familiarize yourself with your blemishes and moles. Most people have a small number of moles. You should be aware of the size, shape, color, and whether or not they are raised, because a change in the appearance of a mole can be a sign of skin cancer. Any noticeable and quick changes should be reported to your physician and followed with regular skin checks. Skin cancer is eminently treatable in most cases if it is discovered early.
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When to Seek Further Consultation for Moles
If you experience a change in appearance or the development of a new mole or blemish, it is important to seek evaluation. The American Association of Dermatologists publishes the ABCDE's of Melanoma describing five features that should warrant evaluation by a skin expert or medical professional.
- Asymmetry: Could the mole be divided into two or more equal appearing parts?
- Border: Is the border of the mole irregular, or faint on one side and defined on another?
- Color: Is the mole a single color or different colors?
- Diameter: Is the mole greater than 6 mm in diameter?
- Evolving size: Have you seen recent changes in size or shape?
If any of these are true, you should have your mole looked at by a medical professional, preferably a dermatologist.
- Orlow I, Satagopan JM, Berwick M, et al. Genetic factors associated with naevus count and dermoscopic patterns: Preliminary results from the Study of Nevi in Children (SONIC). Br J Dermatol. 2015;172(4):1081-9. NCBI Link
- Wiecker TS, Luther H, Buettner P, Bauer J, Garbe C. Moderate sun exposure and nevus counts in parents are associated with development of melanocytic nevi in childhood: A risk factor study in 1,812 kindergarten children. Cancer. 2003;97(3):628-638. NCBI Link
- Strazzulla LC, Kim CC. Atypical moles. JAMA Dermatol. 2016;152(12):1408. JAMA Link
- Tsao H, Bevona C, Goggins W, et al. The transformation rate of moles (melanocytic nevi) into cutaneous melanoma. Arch Dermatol. 2003;139(3):282-8. JAMA Link
- Daniel Jensen J, Elewski BE. The ABCDEF rule: Combining the "ABCDE rule" and the "Ugly duckling sign" in an effort to improve patient self-screening examinations. J Clin Aesthet Dermatol. 2015;8(2):15. NCBI Link
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