Moles that change color or increase in number: Cause for concern?

The sudden change in appearance of a mole (a dermatologist may call it a nevus or nevi, if there are more than one) or a recent uptick in their quantity can certainly provoke anxiety. Luckily, most types of moles are harmless. While some change in the appearance and number may occur over time, if and when the moles in question exhibit signs of concern that?s the time to seek medical attention (read on for more specifics).