Nevi (plural of nevus) is the medical term for a mole, birth mark or beauty mark. Moles are common benign skin lesions made of pigment producing cells known as melanocytes. Melanocytes exist throughout the skin to provide melanin to skin cells. However in moles, these melanocytes cluster into groups rather than be evenly spread out in the skin. They can appear flat, slightly raised or round, and range in color from brown, black, tan, red, pink, blue, and even colorless.
Acquired nevi describe nevi that develop after birth. Most adults have 10-40 common moles, and they continue to develop moles until about age 40. Moles may fade with time as well. People with fair skin tend to have more moles than people of color. People with 10 or more moles are at 12x the risk for developing melanoma, the most serious type of skin cancer. Moles present at birth are known as congenital nevi.
What is a common mole?
A common mole is a spot on the skin that develops when melanocytes cluster together. It is usually round or oval, flat or raised, of a single color including solid pink, brown or black, with a well-defined border, and smaller than 5mm or a 1/4 inch. Common moles can be found anywhere on the body, including underneath fingernails and between fingers and toes. A common mole has the potential to become a melanoma.
What causes a mole?
A mole is a proliferation of melanocytes that can occur before birth (congenital) or afterwards (acquired). Many moles that form during the first few decades of life are thought to be due to sun damage. However, the development of moles has a genetic component as well and the tendency to form moles can be inherited. Sun exposure, immune diseases and some drug treatments can influence the development of new nevi.
What is a dysplastic (atypical) mole?
It is estimated that about one in every 10 Americans has at least one atypical mole. An atypical mole is one that appears irregular. It is larger than a common mole, with irregular and poorly defined borders. Atypical nevi may have several colors, and a varying surface that could be flat, smooth, or scaly. These are some of the features that one sees in a melanoma. These dysplastic moles can appear anywhere the skin is exposed to the sun, but may also appear in areas not exposed to the sun.
While dysplastic nevi are not melanoma, people with dysplastic nevi are at increased risk for melanoma. The more atypical nevi a person has, the greater the chance of developing melanoma. People with atypical moles and a family history of melanoma are at increased risk for melanoma. Moles that look atypical should be evaluated by a dermatologist and monitored on a regular basis.
What are the warning signs of moles?
The ABCDE’s are the warning signs to evaluate atypical moles and diagnose melanoma.
- Asymmetry means the shape is different from one side of the lesion to the other. If you cut the mole in the middle, the halves would not be a mirror image of each other.
- Borders are irregular, notched, scalloped, or blurred, not smooth and even as with common moles.
- Color: Dysplastic moles contains multiple colors including brown or black with red, blue or white spots, unlike common moles which are typically skin colored, brown or black.
- Diameter means the size is larger than 6 mm. However smaller moles with other danger signs could also be melanoma.
- Evolving means the mole is changing shape, size, color or elevation; or another new symptom occurs such as bleeding, itching, crusting. This is the most concerning sign.
Melanoma is the single most important reason for at home skin exams and annual skin checks from your dermatologist.
How are moles diagnosed?
Nevi are diagnosed by visual examination and with the use of dermatoscopy. Dermoscopy can help Dr. Schuering to distinguish benign nevi from cancerous lesions. A dermatoscope is a special magnifying tool that provides diagnostic accuracy for early diagnosis of suspicious nevi.
Dr. Schuering will examine you from head to toe during your annual skin check. Moles can hide inside almost anywhere, including the ears, between the fingers and toes, near the eyes, and in the genital area. If he is concerned about a nevus, he may take a biopsy of the tissue and send it to a laboratory for microscopic evaluation. If he finds dysplastic nevi, he will ask you to watch it over time, and if you have more than five dysplastic nevi, he will recommend that you have your skin examined more frequently. Having a family history of melanoma would also warrant more frequent skin exams.
What is the treatment for moles?
Because most moles are not harmful, they usually do not require treatment, except for cosmetic reasons. Dysplastic moles can be monitored on a regular basis or biopsied for further evaluation, depending on how atypical they appear. The more dysplastic the nevus, the more complete removal is warranted.