Atypical Mole (Dysplastic Nevus)

Atypical moles and dysplastic nevi are acquired melanocytic lesions of the skin whose clinical and histologic definitions are controversial and still evolving. Numerous definitions and criteria have been proposed, including the use of the term atypical moles for clinically abnormal nevi and dysplastic nevi for histologically abnormal nevi.

 

Atypical moles can be inherited or sporadic.

Melanoma can develop from precursor nevi and atypical moles.

 

Atypical moles may arise anytime during a patient's lifetime. Atypical moles can change over time, and new lesions may develop. Individuals with FAMM may have 1 to several hundred atypical moles, whereas those with nonfamilial (sporadic) atypical moles typically have only 1-10 lesions, although they may also present with several hundred lesions.

An individual with atypical moles who is from a family prone to melanoma has a high lifetime risk of developing a melanoma. Rapid and characteristic changes should prompt consideration for excision/biopsy to rule out melanoma.

Dysplastic nevus syndrome

"Dysplastic nevus syndrome" refers to dysplastic nevi with familial malignant melanoma, or risk factors for it.

 

Dysplastic Nevus Syndrome is an autosomal dominant hereditary condition which causes the person to have a large quantity of nevi (moles), often 100 or more. There is a propensity for these nevi to become dysplastic in these individuals. Dysplastic nevi are a precursor to malignant melanoma, and these patients are therefore at a higher risk of developing this malignant form of skin cancer.

 

A slight majority of melanomas do not form in an existing mole, but rather create a new growth on the skin. Nevertheless, those with more dysplastic nevi are at a higher risk of this type of melanoma occurrence.

 

Such persons need to be checked regularly for any changes in their moles and to note any new ones. In 40-50% of cases, the disorder has been linked with germline mutations in the CDKN2A gene, which codes for p16 (a regulator of cell division).

A popular method for remembering the signs and symptoms of melanoma is the mnemonic "ABCDE":

  • Asymmetrical skin lesion.
  • Border of the lesion is irregular.
  • Color: melanomas usually have multiple colors
  • Diameter: moles greater than 6 mm are more likely to be melanomas than smaller moles.
  • Evolution: The evolution (ie change) of a mole or lesion may be a hint that the lesion is becoming malignant.