Moles: What You Need to Know

Moles, which are characterized as a small brownish spot, are a common growth on the skin that develop when your pigment cells (known as melanocytes) grow in clusters. On average, adults have anywhere between 10 and 40 moles. They usually begin to appear around the age of 20, and they are typically found on areas of the body that are above the waist or areas that get frequent sun exposure, which can also cause you to develop more moles, or have pre-existing moles change in size and colour. In some cases, moles can even be found on other areas of the body such as the buttocks, breasts, or scalp.

Moles are classified into three different categories: Congenital, acquired, or atypical. Congenital moles, also known as congenital nevus, affect just 1% of individuals, and are present at birth. These moles also have a higher risk of turning into skin cancer. Acquired moles, which are the most common form of moles, are small in size (usually less than a quarter inch), can develop in early childhood or adulthood, and will not typically develop into skin cancer. They can, however, develop as a result of overexposure to sun. Atypical moles are of more concern as they do have the increased risk of developing into skin cancer. As far as size, they are often larger than that of a pencil eraser and will also have an irregular shape to them. They also tend to be uneven un colour, appearing lighter or reddish in colour, have a dark brown center, or unevenness in colour around their edge. Atypical moles also run in families.

While most people do not think twice about the moles on their body, it can be a good idea to inspect them from time to time to ensure there are no abnormalities, as any suspicious moles could be an indicator of a life-threatening form of skin cancer known as malignant melanoma. When examining your skin, it’s important to know the ABCDEs of moles:

A = Asymmetry: One half will often look different than the other.

B = Irregular Border: This usually means the mole will have a poorly defined border.

C = Varied Colour: A mole that has multiple shades of black, red, brown, or white.

D = Large Diameter: Larger than that of a pencil eraser.

E = Evolving: A mole that changes in shape, size or colour over time.

You should also pay attention to any new moles that develop, especially if you’re over the age of 20, as well as any moles that become bothersome — which can include pain, itching, and even bleeding. It is important to note that while cancerous moles can change in appearance, and may even itch, ooze or bleed, they typically do not cause pain.

If a mole looks suspicious, physicians will typically refer patients to a dermatologist for further examination. In some cases, a biopsy may be taken of the mole to test for cancer. This biopsy will also let the dermatologist known just how deeply the skin cancer has penetrated the skin, which will help them to determine the necessary treatment should skin cancer be confirmed. The most common treatment for moles that turn into malignant melanoma is through complete removal of the mole using a surgical tool known as a scalpel and is generally done under local anesthetic. In the event that the melanoma has spread to other internal organs of the body, treatment then becomes much more complex, and can include things like chemotherapy, radiation therapy, as well as immunotherapy.

Originally published at on January 7, 2019.



Dr. Ali Ghahary is a Family Physician in Vancouver, British Columbia, Canada.

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