A17. Pigmented naevi

From greek.doctor
  • 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