Naevus

• A nevus is a benign lesion of melanocytes in the skin or oral mucosa
• Can be pigmented or non-pigmented (most are pigmented)
• Histological classification
  • Junctional nevi
    • Flat, well-demarcated brown macules
    • Grows in the epidermis at the dermal-epidermal junction
  • Compound nevi
    • Elevated
    • Grows in the epidermis at the dermal-epidermal junction and in the dermis
  • Dermal nevi
    • Elevated
    • May be hard and grow hair
    • Grows in the dermis only
• Clinical classification
  • Congenital
    • Small (< 1,5 cm)
    • Medium
    • Giant (> 20 cm)
  • Acquired
    • Common acquired nevus
      • < 6 mm
      • Symmetric
      • Homogenous surface
      • Even pigmentation
      • Round or oval shape
      • Sharply demarcated border
    • Atypical/dysplastic nevus
      • Share some similarities to melanoma
      • Must be differentiated from melanoma
      • Fried egg or target-shaped
      • May evolve
      • Atypical colour
      • Irregular, poorly demarcated
    • Spitz nevus
      • Not brown, rather pink, tan, red, etc.
      • In children
    • Halo nevus
      • Nevus surrounded by halo of depigmentation
    • Reed nevus
      • Very dark
      • On limbs
    • Nevus spilus
      • Tan macule speckled with smaller, darker macules
    • Blue nevus
• Dysplastic nevus syndrome
  • Also called familial atypical multiple mole and melanoma syndrome (FAMMM)
  • High number (> 50) of common and atypical nevi and family history of melanoma
  • Almost 100% of developing melanoma
• Diagnosis
  • History
    • Family history?
    • History of skin lesions?
    • History of sunburns?
    • When did nevus appear?
    • Has it changed?
  • Physical examination
    • Assess skin type
    • Examination with dermoscope
    • ABCDE
    • Ugly duckling sign