Acquired Melanocytic Nevus
Melanocytic nevi are a benign cluster of melanocytic nevus cells that arise as a result of proliferation of melanocytes at the epidermal-dermal junction.
The greater the number of nevi present, the greater is the risk for development of melanoma.
Sun exposure during childhood, immunosuppression an important determinant of the number of melanocytic nevi.
- Clinical Manifestations
Nevocellular nevi have a well-defined life history and are classified as junctional, compound, or dermal in accordance with the location of the nevus cells in the skin.
- Some nevi, particularly those on the palms, soles, and genitalia, remain junctional throughout life.
- More than 90% of nevi are junctional; melanocyte proliferation occurs at the junction of the epidermis become compound as melanocytes migrate into the papillary dermis to form nests at both the epidermal-dermal junction and within the dermis.
- If the junctional melanocytes stop proliferating, nests of melanocytes remain only within the dermis, forming an intradermal nevus.
- With maturation, compound and intradermal nevi may become raised, dome shaped, verrucous, or pedunculated.
Distinctly elevated lesions are usually intradermal. With age, the dermal melanocytic nests regress and the nevi gradually disappear.
- Prognosis And Treatment
Acquired pigmented nevi are benign.
Changes indicative of excisiom:
- Rapid increase in size
- Development of satellite lesions
- Variegation of color, particularly with shades of red, brown, gray, black, and blue
- Pigmentary incontinence
- Notching or irregularity of the borders
- Changes in texture such as scaling, erosion, ulceration, and induration
- Regional lymphadenopathy