Moles, or nevi, are clusters of pigmented cells that typically appear as dark brown spots and can develop anywhere on the body. Moles are caused by irregular melanocyte cell growth in the skin. Often overlooked because of their commonality, they are usually the first indicators of skin cancer or malignant melanoma, the most serious form of skin cancer. Appearing and disappearing throughout a person’s life, they have the ability to constantly morph and can vary in size, shape and color. Congenital nevi, or moles appearing at birth, are less common and have a higher risk of melanoma than other forms. If you are over 30 and begin to notice new moles, you should make an appointment to get a skin exam.


Self-examination and awareness are important first steps in detection and prevention. Keep track of any changing areas of skin and moles. Wearing sunscreen and limiting sun exposure are important roles in skin health.

Remember the ABC identifiers during self-examination:

  • A  for Asymmetry. Look for moles with irregular shapes, such as two very different-looking halves.
  • B for border. Look for moles with irregular, notched or scalloped borders the characteristics of melanomas.
  • C for color. Look for growths that have many colors or an uneven distribution of color.
  • D for diameter. Look for growths that are larger than about 1/4 inch (6 millimeters).
  • E for evolving. Look for changes over time, such as a mole that grows in size or that changes color or shape. Moles may also evolve to develop new signs and symptoms, such as new itchiness or bleeding.