Moles are caused when melanocytes grow in clusters.

Some people have moles from birth, while other moles can develop with age. Moles can appear anywhere on the body and. They vary from round to oval shape. They can be flat or raised, smooth or wrinkled. Moles are usually brown, tan or dark colors. However, their colors may change over time.

Moles can be considered unusual when any of the following symptoms or conditions are observed:

• Variation in color, usually turning black
• Irregular borders and colors on the area surrounding the mole  
• Irregular surface, such as cracked and scaly skin or raised and hard bumps
• Fluid seeping from the mole, bleeding, crusting
• Constant pain that does not ease 

As part of the diagnostic process, the doctor will conduct a thorough skin examination and ask about the symptoms. If necessary, a tissue sample may be taken for further investigation.

If the mole is considered unusual and/or is deemed at risk of becoming cancerous, the doctor will surgically remove it. If cancerous cells are found after an examination, additional surgery may be required to cut out the mole and the surrounding margin. 

In order to prevent moles from becoming unusual (or causing cancer): 

• Avoid overexposure to the sun. Use a hat, protective clothing and sunscreen with an SPF of at least 30 if you must be outdoors.
• Look for moles with irregularities and seek medical attention for any unusual moles.
• Have your moles regularly checked by a doctor every 12 months. If you have many unusual-looking moles or family history of moles that have turned into cancer, see the doctor more frequently, such as every 6 months.