Congenital Melanocytic Nevus

Congenital melanocytic nevi (CMN) are moles that are present at birth or become visible during the first year of life. They enlarge with the child and are classified as small, medium, large or giant based on their projected final adult size. When do we worry? Location
  • Over the lower back/ buttock/ garment location as there is higher association with neurocutaneous melanosis
  • This in turn leads to neurodevelopmental disorders and risk of leptomeningeal melanoma
Size
  • Large/Giant CMN have higher risk of melanoma
Satellite nevi
  • Large CMN and more than 20 satellites had a 5.1 fold increased risk of neurocutaneous melanosis compared with large CMN with 20 or fewer satellites1.
Close up detail of the bare skin on a man back with scattered moles and freckles. Checking benign moles. Sun effect on skin. Birthmarks on skin

Treatments available in the clinic include:

If cosmesis is a concern, treatments with Carbon dioxide laser or surgery can be performed. A less conventional mode of treatment is the Pulsed dye laser, typically for blood vessel/vascular lesions but has been shown to be effective. More than anything, sun protection and being familiar with the ABCDE (asymmetry, border irregularity, colour variegation, diameter greater than 0.6 cm, evolution) rule for melanoma skin surveillance is of paramount importance. However, of even greater importance, is to regularly feel the mole for any nodules/lumps. In addition, in children, a modified ABCD (amelanotic, bleeding, bump, colour uniformity, de novo, any diameter) has been introduced as pediatric melanoma can present differently from adults.

 

References

  1. Marghoob AA et al. Number of Satellite Nevi as a correlate for neurocutaneous melanocytosis in patients with large congenital melanocytic nevi. Arch Dermatol. 2004;140:171-175.
  2. Cordoro KM et al. Pediatric melanoma: Results of a large cohort study and proposal for modified ABCD detection criteria for children. J Am Acad Dermatol. 2013;68:913-925.