Mole

Aka: Mole, Dermal Nevus, Junctional Nevus, Melanocytic Nevus, Compound Nevus, Nevocellular Nevus, Nevus, Common Mole, Nevi, Junctional Nevi, Compound Nevi, Intradermal Nevi

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II. Epidemiology

  1. Onset after age 6-12 months, and forming new nevi until age 50 years, when they begin the recede
  2. Common Incidence in Caucasian skin
    1. Typical Caucasian adults have 20 nevi (some adults may have 40-50)
    2. Most concentrated on sun exposed areas
  3. Less numerous in pigmented skin (e.g. Black)

III. Physiology

  1. Melanocytes
    1. Melanin producing cells in the Stratum Basale (bottom layer) of the Epidermis
    2. Contributes to overall skin, hair, eye pigmentation
  2. Nevus Cells
    1. A type of Melanocyte that is larger and is without Dendrites
    2. Nevus cells form nests at the dermal-epidermal junction
  3. Nevus cells mature from Type A to Type C cells and migrate downward from Epidermis to Dermis
    1. Type A Nevus Cell: Epitheloid (epidermal)
    2. Type B Nevus Cell: Lymphocytoid
    3. Type C Nevus Cell: Neuroid (dermal)

IV. Classification: Nevi

  1. Over decades, moles descend into the Dermis and progress from Junctional Nevi to Compound Nevi and then to dermal nevi
  2. Junctional Melanocytic Nevus
    1. Flat to slightly elevated nevi with sharp borderss, and typically hairless
    2. Uniformly tan, brown or black nevi starting at 1-2 mm and expanding to 4-6 mm
    3. Localized at the dermoepidermal junction
  3. Compound Melanocytic Nevus
    1. Slightly elevated to dome shaped Papule
    2. Flesh or brown colored nevi
    3. May have hypopigmented surrounding ring known as Halo Nevus
    4. Start at the dermal-epidermal junction and extend into the Dermis
  4. Dermal Melanocytic Nevus
    1. Dome shaped nevi which may have a verrucous, pedunculated or polypoid surface
      1. Elevation off skin predisposes to local Trauma, irritation and bleeding
      2. Distinguish from nodular Melanoma which may have a similar appearance
    2. Nevi may be flesh colored or pink to brown or black, diameter may approach 1 cm
    3. Localized to the Dermis
    4. Degeneration into Melanoma is rare

V. Signs

  1. General characteristics
    1. Small (< 1 cm)
    2. Sharply circumscribed
    3. Soft, round or oval Macules or dome shaped Papules
  2. Junctional Nevus Characteristics
    1. Minimally raised Papule or flat Macule
    2. Smooth regular borders
    3. Tan, brown or dark brown color
    4. Distribution
      1. Palms and soles
      2. Trunk
      3. Face
      4. Upper extremities
      5. Lower extremities
  3. Dermal Nevus
    1. Skin-colored, tan or brown colored Papules
    2. Round, dome-shaped, well circumscribed Papules
    3. Distribution
      1. Most common: Face and neck
      2. Other locations: Trunk, extremities

VI. Differential Diagnosis

  1. Junctional Nevus larger than 1 cm
    1. Congenital Nevus
    2. Dysplastic Nevus
  2. Dermal Nevus
    1. Basal Cell Carcinoma
    2. Dysplastic Nevus

VII. Management

  1. See Atypical Nevus

VIII. References

  1. Habif (2003) Clinical Dermatology, 4th ed.. Mosby, p. 773-813

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