Health A-Z

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When melanocytes become cancerous, they are called melanomas. It is important to examine your moles regularly to look for any suspicious changes. Get someone else to inspect your scalp and other areas that are hard to see. Watch for the early warning signs of melanoma by using the ABCDE criteria:

  • Asymmetry

  • Border irregularities

  • Color variation (different colors within the same mole)

  • Diameter greater than 6 millimeters (larger than a pencil eraser)

  • Evolving (a new mole developing)

Practice safe sunning. Never sunbathe or visit a suntan parlor for the sake of tanning. Use high-SPF sunscreen when outdoors, wear protective hats and clothing, and avoid the outdoors when the sun is most intense, from 11 a.m. to 3 p.m. Sweating or swimming can cause sunscreen to wash off, even if it is labeled as "waterproof". Reapply sunscreen often.

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From Health A-Z, Harvard Health Publications. Copyright 2007 by the President and Fellows of Harvard College. All rights reserved. Written permission is required to reproduce, in any manner, in whole or in part, the material contained herein. To make a reprint request, contact Harvard Health Publications. Used with permission of StayWell.

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