clinical features distinguishing atypical from benign nevi

Clinical manifestations

Color

• benign nevi: uniform tan or brown
• atypical nevi:
  • variable mixtures of tan, brown, black or red/pink within a single nevus
  • nevi may look very different from each other

Shape

• benign nevi:
  • round
  • sharp, clear-cut borders between the nevus & the surrounding skin
  • may be flat or elevated
• atypical nevi:
  • irregular borders
  • pigment may fade off into surrounding skin
  • macular portion at the edge of the nevus

Size

• benign nevi: generally < 6 mm in diameter
• atypical nevi:
  • generally > 6 mm in diameter
  • may be > 10 mm in diameter
  • occasionally < 6 mm in diameter

Number

• benign nevi:
  • in a typical adult, 10-40 nevi are scattered over the body
  • 15% of individuals have no nevi
• atypical nevi:
  • often > 100 nevi
  • occasionally, may be only one nevus

Location

• benign nevi:
  • generally on sun-exposed surfaces of the skin, above the waist
  • scalp, breasts & buttocks are rarely involved
• atypical nevi:
  • sun-exposed areas
  • the back is the most common site
  • dysplastic nevi may also be seen on the scalp, breasts & buttocks

Additional terms

• nevus