Blue Nevus

 

Epidemiology:

    •  

 

Common sites:

    • common blue nevus:
      • dorsa of hands and feet
    • cellular blue nevus:
      • lower back or buttocks

 

Gross features:

    • common blue nevus:
      • < 1.0cm
      • slightly elevated or dome-shaped
    • cellular blue nevus:
      • > 1.5cm
      • bluish dermal nodule or plaque

 

Histologic features:

    • common blue nevus:
      • well circumscribed, unencapsulated
        • restricted to dermis, occasionally into subcutaneous fat
        • predilection for adnexal structures
      • spindle cells with melanin pigment
        • bipolar or dendritic shapes
      • wrapping around bundles of collagen
      • melanophages
    • cellular blue nevus:
      • well circumscribed, unencapsulated
        • restricted to dermis
      • unpigmented spindle cells (some are pigmented upon close examination)
      • cellular mass of interweaving fascicles

 

Immunophenotype:

Marker:

Sensitivity:

Specificity:

 

 

 

 

Molecular features:

    • GNAQ mutation (majority)

 

Other features:

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