One half of a mole or birthmark does not match the other half.
The edges of a mole or spot are uneven, scalloped, or poorly defined.
The color of a mole or spot is not uniform. It may have different shades of brown, black, red, blue, or white.
The size of a mole or spot is larger than 6 millimeters (about the size of a pencil eraser) or is growing in size.
Any changes in size, shape, color, elevation, or symptoms of a mole or spot over time should be monitored closely.
Moles or spots that itch, bleed, or develop a crust may be concerning.
Skin lesions that do not heal within a few weeks or develop into open sores should be examined by a healthcare professional.