• Medical Author:
    Gary W. Cole, MD, FAAD

    Dr. Cole is board certified in dermatology. He obtained his BA degree in bacteriology, his MA degree in microbiology, and his MD at the University of California, Los Angeles. He trained in dermatology at the University of Oregon, where he completed his residency.

  • Medical Editor: William C. Shiel Jr., MD, FACP, FACR
    William C. Shiel Jr., MD, FACP, FACR

    William C. Shiel Jr., MD, FACP, FACR

    Dr. Shiel received a Bachelor of Science degree with honors from the University of Notre Dame. There he was involved in research in radiation biology and received the Huisking Scholarship. After graduating from St. Louis University School of Medicine, he completed his Internal Medicine residency and Rheumatology fellowship at the University of California, Irvine. He is board-certified in Internal Medicine and Rheumatology.

Skin Cancer Slideshow

What types of moles are there?

There are three basic types or groups of moles: regular and symmetrical, irregular, and cancerous. Irregular moles are also called atypical moles. Regular moles are typically benign and harmless. Regular moles are usually symmetrical, have regular borders, uniform color, and are about the size of a pencil eraser or smaller. Regular moles may be flat or raised. The presence of hair growing from a mole is unrelated to its cancer potential.

Irregular or atypical moles are usually asymmetrical, with irregular borders, multiple colors, and tend to be bigger than the size of a pencil eraser. Irregular moles are often flat or nearly flat. Having more than 20-25 irregular moles may increase the person's overall risk of developing melanoma. The presence of a giant congenital mole greater than approximately 8-10 inches in size also may confer an increased risk of melanoma. Irregular moles signal the potential for developing melanomas over time. Irregular moles themselves rarely turn into melanoma or cancer.

Cancerous moles called melanomas, are highly irregular and are often asymmetrical. Rarely, regular moles may evolve into a melanoma over time. It is important to watch all moles closely for change or atypical features. In those with greater than 50 moles or several abnormal moles, monthly skin self-examinations and at least annual full-body moles exam by a dermatologist are important in the early detection of abnormal moles and melanoma.

  • A -- Asymmetrical
  • B -- Irregular borders
  • C -- Multiple colors
  • D -- Diameter bigger than a pencil eraser
  • E -- Evolving, changing, or new

Irregular moles can occur anywhere on the body but are most commonly located on sun-exposed skin, especially on the upper back and shoulders where people frequently get their most severe sunburns. The risk of melanoma is greater on chronically sun-exposed skin like the shoulders, upper back, head, and neck. Ears are a particularly common site of atypical moles because of the difficulty in applying sunscreen and frequent sun exposure. Women have increased risks of atypical moles, particularly on the lower leg and calf. Any new or changing irregular mole on a woman's calf warrants immediate medical evaluation.

Medically Reviewed by a Doctor on 11/12/2015

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