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Melanoma skin cancer sign: Diameter

A mole, showing its width compared to a pencil eraser.

Melanoma is the most serious type of skin cancer. The most important warning sign of melanoma is a change in the size, shape, or colour of a mole or other skin growth, such as a birthmark.

  • A change in diameter (width) is one thing to watch for. Call your doctor if:
    • The width of a mole or skin growth is larger than 6 mm (1/4 inch), or about the size of a pencil eraser.
    • Any mole seems to be growing, even if it is still smaller than 6 mm (1/4 inch).

Current as of: October 25, 2023

Author: Healthwise Staff
Clinical Review Board
All Healthwise education is reviewed by a team that includes physicians, nurses, advanced practitioners, registered dieticians, and other healthcare professionals.

This information does not replace the advice of a doctor. Healthwise, Incorporated, disclaims any warranty or liability for your use of this information. Your use of this information means that you agree to the Terms of Use. Learn how we develop our content.

This information does not replace the advice of a doctor. Healthwise, Incorporated, disclaims any warranty or liability for your use of this information. Your use of this information means that you agree to the Terms of Use. Learn how we develop our content.

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