Do dysplastic moles develop into melanomas?

6 Dec

Atypical or “dysplastic” moles are usually irregular, odd-looking moles that can sometimes appear similar to a melanoma.

For many years, they were considered to be pre-cancerous. In other words, it was thought that if an atypical mole was untreated it would eventually develop into a melanoma — similar to the dysplastic cells sometimes discovered on a Pap smear of the cervix. Many patients of our clinic have had multiple dysplastic moles removed as a “precaution” to prevent melanoma. Other patients with dysplastic moles diagnosed at an initial biopsy have had them re-excised with wider margins “just in case”, leaving a much larger scar with a higher rate of complications.

In fact, the word dysplastic is not really suitable for this type of mole, since it does not seem to have any higher risk of developing into a melanoma than a normal-looking mole.

A study published in 2012 examined over 100 patients with dysplastic moles diagnosed between 1980-1989. These moles were removed with very narrow margins (less than 0.2mm). The study found no melanomas occurred at the site of excision of the dysplastic mole, with more than 20 years follow-up of some patients. The authors concluded that dysplastic moles do not need to be re-excised.

Other authors have shown that melanomas are no more likely to arise from a dysplastic mole.

Our approach at Spot Check Clinic:

  • If a mole appears to be dysplastic with a low risk of it actually being a melanoma, we prefer to perform repeat dermoscopic photography to look for changes which might suggest that it is in fact an early melanoma. If an apparently dysplastic mole has changed after 3 months, we would consider removing it since there is now more suspicion that it could be a melanoma
  • If we remove a suspicious mole and the pathology confirms that it is a dysplastic mole, we would not normally re-excise the mole.
  • Patients with a history of dysplastic moles, especially if there are more than one, should have an annual full body skin check.
  • If the person has many dysplastic moles, we might recommend total body photography (mole mapping) to document changes and assist earlier detection of new or changing spots.