A mole (nevus) is a pigmented (colored) spot on the outer layer of the skin (epidermis).
Moles can be round, oval, flat, or raised. They can occur singly or in clusters on any part of the body. Most moles are brown, but colors can range from pinkish flesh tones to yellow, dark blue, or black.
Most moles are benign (not cancerous), but atypical moles (dysplastic nevi) may develop into malignant melanoma, a potentially fatal form of skin cancer. Atypical moles are usually hereditary. Most are bigger than a pencil eraser, and the shape and pigmentation are irregular.
The cause of moles is unknown, although atypical moles seem to run in families and result from exposure to sunlight.
A mole should be evaluated by a dermatologist.