The only way to confirm a mole is cancerous is through tests administered by a doctor, such as biopsies, imaging tests and blood tests, according to the American Cancer Society. However, there are certain warning signs that indicate a mole may have become cancerous. New spots on the skin or moles that change in appearance should be evaluated by a doctor.
People with a family history of melanoma should check their skin once a month to look for new or changing moles, recommends WebMD. When performing screenings, individuals should use a full-length mirror to aid in checking every area of the skin, including hidden areas such as the scalp and in between the fingers and toes. Women most often get melanoma on the legs, while men frequently get melanoma on the torso. Moles with asymmetric shapes, irregular borders, multiple colors, large diameters or changing features should be evaluated by a dermatologist.
Patients who find abnormal moles should visit a doctor, explains the American Cancer Society. Dermatologists can estimate a patient's risk factors for developing melanoma and analyze moles with a magnifying lens. If a mole looks unusual, the doctor may take a biopsy of the skin, which is then sent to a lab for further analysis.