Those 'beauty marks' on our skin -- benign, pigmented lesions known as moles -- are typically harmless. But a small percentage of moles turn into melanomas, a potentially lethal form of skin cancer.

"There are a number of different types of lesions on the skin," says Dr. James Grichnik, a dermatologist and associate professor of medicine at Duke University Medical Center. "Moles are lesions that people usually start to develop during adolescence. They can be born with them as well. Moles tend to be pigmented areas, and the skin surface over them tends to be relatively smooth.

"Such lesions can be initiated through a variety of factors, one of which is thought to be sun exposure, particularly during childhood," Grichnik adds. "There is also a genetic element, and moles can run in families. So can melanomas."

It's vital to catch melanomas early, when they're curable, Grichnik says. "Once they get deeper into the skin, the risk of having that tumor spread continues to increase."

High-risk individuals include those with many moles, large irregular moles and a personal or family history of melanoma.

"Melanomas are actually quite rare in terms of the overall number of moles, but if an individual has a mole that just doesn't match the others, perhaps appearing to be more irregular, or if it's growing or changing, then it's definitely worth seeing a physician," Grichnik says.

To aid in mole surveillance, Grichnik developed a mole-mapping program that uses a set of computerized, high-resolution photos of the body to track moles over time. "We create a good set of full-body photos," he explains. "This allows us to identify lesions that may be changing over a period of time. We then sort out the moles that may be potential melanomas. We can then focus in on the lesions that may be dangerous to the patient and also avoid doing unnecessarybiopsies."

Grichnik emphasizes that high-risk individuals should be actively involved in mole monitoring.

"Keep an eye on your moles," he says. "It's much more likely that between the patient and the physician, if a melanoma develops, they'll be able to get it early and in a more curable timeframe."

Grichnik says people can also help prevent mole development in children by keeping them out of the midday sun and by always using sun block and other protective agents. For those individuals at higher risk, he also recommends a monthly self-examination.

For more information about preventing and treating melanomas, visit the American Academy of Dermatology Web site at www.skincarephysicians.com/melanomanet/index.html