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  • Cynthia M. Johnson, MA
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Moles are spots on the skin where pigmented (colored) 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 moles 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
  • Uneven 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 Cancer Sign: Irregular Border on Mole NULLjpgSkin Cancer Sign: Irregular Border on Mole NULL\\filer01\Intellect\images\si55550315.jpgCopyright © 2002 Nucleus Communications, Inc. All rights reserved.21NULL2002-10-012553912526_11669Copyright © Nucleus Medical Media, Inc.

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 symptoms and past health. 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 do not like having the mole or it gets 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:





  • Common benign skin lesions. EBSCO DynaMed website. Available at:
  • Common moles, dysplastic nevi, and risk of melanoma. National Cancer Institute website. Available at:
  • Dysplastic nevus. EBSCO DynaMed website. Available at:
  • Moles: who gets and types. American Academy of Dermatology website. Available at:
  • Perkins A, Duffy RL. Atypical moles: diagnosis and management. Am Fam Physician. 2015;91(11):762-777.
  • Sunscreen FAQs. American Academy of Dermatology website. Available at:
Last Updated:

This content is reviewed regularly and is updated when new and relevant evidence is made available. This information is neither intended nor implied to be a substitute for professional medical advice. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with questions regarding a medical condition.