Updated: 1/25/2018

Nevus

Topic
Review Topic
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Snapshot
  • A 40-year-old woman presents to her dermatologist for concern of several moles on her nose, back, and stomach. She reports having had these moles since birth. They have not changed in color, shape, or size. On physical exam, there is a 2 mm brown papule on her nose, a 3 mm light brown macule on her upper back, and a 4 mm dark brown papule on her stomach. Dermatoscope reveals no features concerning for melanoma. The patient is reassured about her prognosis.
Introduction
  • Clinical definition
    • benign tumors made of nevus cells, which are derived from melanocytes
      • also known as “moles”
    • there are three types of common moles based on location in the skin, representing a sequential progression
      • junctional nevi are located at the dermoepidermal junction
      • compound nevi are partially in the dermis
      • intradermal nevi are completely in the dermis
  • Epidemiology
    • incidence
      • very common and affects almost every person
    • demographics
      • female > male
      • peak incidence in 40-50 years of age
    • risk factors
      • sun exposure
      • light-skinned individuals
      • neonatal phototherapy
  • Pathogenesis
    • nevi may result from increased melanin or increased production of melanocytes
      • they originate from neural crest stem cells that migrate to the epidermis and subsequently to the dermis
      • mutations in BRAF are often detected
  • Prognosis
    • the number of nevi typically increases until 40-50 years of age and subsequently decreases
    • they typically remain uniform shape, color, and pattern
    • nevi have a very low risk of malignancy
Presentation
  • Physical exam
    • junctional nevi
      • flat (macular)
      • brown to black macule
    • compound nevi
      • slightly elevated or dome-shaped
      • brown or light brown papule
    • intradermal nevi
      • dome-shaped, warty, pedunculated, or sessile
      • brown or flesh-colored papule
Studies
  • Making the diagnosis
    • most cases are clinically diagnosed with the help of dermatoscopy
Differential
  • Melanoma
    • distinguishing factor
      • non-uniform or changing color, shape, or size
Treatment
  • Management approach
    • nevi are typically not removed unless for cosmetic reasons or if there is a strong suspicion of malignancy
  • Non-operative
    • removal
      • indications
        • changing lesion (in size, color, or shape)
        • suspicion of malignancy
        • bothersome or cosmetically unsightly
Complications
  • Irritation
    • if the mole is pedunculated or elevated, repetitive trauma may cause pain, irritation, or bleeding
 

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