Pre-cancerous lesions (such as actinic keratoses or AKs) are scaly or crusty bumps that forms on the skin surface that have the potential to become cancerous. They can be very small or as large as a penny. They can vary in color, lightness, and other features. The scale or crust is dry, and rough, like a hoof, and is often recognized easier by touch rather than sight. AKs may disappear for a time only to reappear later. AKs usually make their appearance on parts of the body that get lots of sun exposure and sun damage, like the face, ears, scalp, neck, backs of hands and forearms, and lips. AKs tend to lie flat against the skin of the head and neck but tend to be elevated on arms and hands.