Symptoms:

Each type of birthmark has its own appearance:

• Cafe-au-lait spots are light tan, the color of coffee with milk.
• Moles are small clusters of colored skin cells.
• Mongolian spots (also called Mongolian blue spots) are usually bluish or bruised-looking. They usually appear over the lower back or buttocks, but can also appear in other areas, including the trunk or arms.

Other symptoms of birthmarks:

• Abnormally dark or light skin
• Contain hair
• Skin lesion
• Skin lumps
• Textured -- smooth, flat, raised, or wrinkled

Signs and tests:

Diagnosis is usually made based on the appearance of the skin area. A biopsy may be performed to look for cancerous changes.