White moles are uncommon and they should always be checked by a medical professional. According to the National Cancer Institute, common moles are brown or pink and have an even color.
Most common moles are not cancerous, but any unusual color or color change should be reported to a medical professional. Most moles have only one or two colors, so anything more than that may be a symptom of melanoma. According to WebMD, a mole that has shades of white, red, blue or black may be a symptom of skin cancer. Seeing a dermatologist is essential if the mole changes in size or has irregular, blurred or ragged borders. Bleeding is another symptom that requires immediate attention.
The dermatologist examines a suspect mole and takes a skin biopsy whenever appropriate. Depending on the results, further tests may be required and the doctor may decide to remove the mole. Sometimes, moles can be surrounded by a ring of depigmentations, which creates a white halo around them. These halo moles are common during pregnancy and are usually benign, but it is important to have them checked by a dermatologist, especially in the case of women who are at an increased risk for developing melanoma.