Melanoma is the most serious type of skin cancer. The most important warning sign of melanoma is a change in the size, shape, or color of a mole or other skin growth, such as a birthmark.

• A change in diameter (width) is one thing to watch for. Call your doctor if:
  • The width of a mole or skin growth is larger than 1/4 inch (6 mm), or about the size of a pencil eraser.
  • Any mole seems to be growing, even if it is still smaller than 1/4 inch (6 mm).