Moles are spots on the skin where pigmented cells have clustered together. They often appear as light to dark brown spots on the skin. They can be flat or raised. They are benign (harmless) in most people.

Dysplastic nevi are atypical (not typical) moles. They can turn into a type of skin cancer called melanoma.


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Moles develop from cells in the skin called melanocytes. Normally, these cells are evenly spread out. A mole happens when the cells form a cluster.

Risk Factors

The risk of this problem is higher in people who have:

  • Moles that are present at birth
  • Family members with moles
  • Had excess sun exposure


Most people will have benign moles that appear at birth through the teen years. Most adults have 10 to 40 moles.

Benign moles can appear anywhere on the body. They may be:

  • Light to dark brown, but can also be yellow-brown or flesh tone
  • One color
  • Round or oval with clear edges
  • Flat and smooth, but sometimes they may become raised, rough, or grow hair

Signs that a mole may be atypical are:

  • A sudden change in size, color, shape, texture, or how they feel
  • Large size—¼ inch or more across
  • A mixture of colors, often including black
  • Irregular edges
  • An abnormal surface that is:
    • Scaling
    • Flaking
    • Oozing
    • Bleeding
    • Open with a sore that will not heal
    • Hard with a raised lump
  • Itching or pain
  • Abnormally colored skin around it

Irregular Border on Mole

Skin Cancer Sign: Irregular Border on Mole
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When Should I Call My Doctor?

Call your doctor if you:

  • Are worried about a mole that does not look the same as the others
  • Are over 30 years of age and find a new mole


The doctor will ask about your symptoms and health history. A physical exam will be done. It will focus on the skin.

The mole may need to be tested. This can be done with a biopsy.


Benign moles do not need to be treated. Some people may have them removed if they are unsightly or get irritated.

Atypical moles may be watched for changes or removed. Atypical moles that are or may be cancerous can be removed with surgery. The mole tissue is examined under a microscope.


Not all moles can be prevented. The risk of some moles may be lowered with skin protection, such as:


American Academy of Dermatology
American Cancer Society


Canadian Dermatology Association


Common benign skin lesions. EBSCO DynaMed website. Available at: Accessed March 12, 2021.
Common moles, dysplastic nevi, and risk of melanoma. National Cancer Institute website. Available at: Accessed March 12, 2021. Accessed June 20, 2018.
Dysplastic nevus. EBSCO DynaMed website. Available at: Accessed March 12, 2021.
Moles. American Academy of Dermatology website. Available at: Accessed March 12, 2021.
Perkins A, Duffy RL. Atypical moles: diagnosis and management. Am Fam Physician. 2015 Jun 1;91(11):762-777.
Sunscreen FAQs. American Academy of Dermatology website. Available at: Accessed March 12, 2021.
Last reviewed December 2020 by EBSCO Medical Review Board Daniel A. Ostrovsky, MD
Last Updated: 03/12/2021

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