Skip to main content

Stock photo | Thinkstock

The question

I've noticed a mole that I've had for years has recently increased in size and changed its shape. It's small and doesn't bother me but is this something I should worry about?

The answer

It's important that you have noticed a change in your mole as early detection is the best protection against serious skin diseases since most are treatable.

Moles, or nevi as they are known medically, are groups of pigmented cells in the skin that can range in colour, shape and size and be anywhere on the body. On average, a person can have between 10 and 40 moles, but this number can change throughout your life with some moles appearing during adulthood and others disappearing with age.

Most moles are harmless, but in some cases they can become cancerous. There are many types of skin cancer but the most serious form is melanoma. According to the Canadian Dermatology Association, melanoma is the seventh most frequent cancer in Canada. Melanoma can occur anywhere on the body but it is most frequently found on the back for men and on the back and legs for women.

The best way to monitor for potential problems is to know your moles by being familiar with their shape, size and location. Remember to check areas that aren't exposed to sunlight such as the scalp, armpits and feet. For areas that are hard to see such as the back, use a handheld mirror or get a friend or family member to take a look.

An easy tool to use at home when checking your moles is the ABCDE rule. If you notice any of these changes, see your doctor:

A – Asymmetric shape: Moles with two different halves may have a higher risk of skin cancer.

B – Irregular border: Look for moles with notched or scalloped edges or borders that are not smooth in shape. Also beware of any redness developing around a mole.

C – Colour change: If a mole has many colours or an uneven distribution or is darkening in colour, get it checked out.

D – Diameter: Growths larger than 6mm can be at higher risk of being cancerous.

E – Evolving: Look for changes over time, such as a mole that grows in size or changes in colour or shape. Also beware of new signs and symptoms, such as itchiness or bleeding.

In addition to the ABCDE rule, another helpful tip is to note that most moles on the body will look similar to each other. So if you notice a mole that's the "odd one out," this could signal something is wrong.

Along with monitoring moles, you should know if you have any of risk factors for skin cancer, including:

Personal or family history of melanoma

The presence of many moles (more than 50)

History of severe sun burns or history of excessive sun exposure

Light-coloured skin and blond or red hair

Diseases that suppress the immune system

If you are at higher risk for skin cancer, have your family doctor or a dermatologist check your moles at least once a year. Some health practitioners offer "mole mapping," photo documentation of your moles, which will provide a reference of their size and shape.

In addition to early detection, remember the best prevention for skin cancer is to reduce sun exposure, use sunscreen regularly and avoid burns.

Send family doctor Sheila Wijayasinghe your questions at She will answer select questions, which could appear in The Globe and Mail and/or on The Globe and Mail web site. Your name will not be published if your question is chosen.

Read more Q&As from Dr. Wijayasinghe.

Click here to see Q&As from all of our health experts.

The content provided in The Globe and Mail's Ask a Health Expert centre is for information purposes only and is neither intended to be relied upon nor to be a substitute for professional medical advice, diagnosis or treatment.