Color is often another indicator of trouble. Moles that show different shades can be cancerous. Cancerous lesions can be multiple shades of tan, brown or black. It's also common to find melanomas that have red or blue coloring to them. 

The diameter of a melanoma is usually larger than a pencil eraser. Sometimes when detected early, they can be smaller, but it's important to watch large moles or lesions closely because they may be cancerous. 

An evolving mole may be a sign of cancer. A mole that changes size, shape, color, elevation or another characteristic may be a cancerous mole. Additionally, other changes such as bleeding, itching or crusting are signs of trouble. 

If you see new growths or notice that skin lesions have changed, then it's important to see a dermatologist as soon as you can. Melanoma is a survivable cancer when caught in the early stages. When allowed to metastasize – in other words, spread to internal organs, the survival rate decreases dramatically. Reduce your risk by not exposing yourself to the sun and having a dermatologist check your skin annually.