Congenital melanocytic nevus. Clinical and dermoscopic signs of malignancy.

Abstract

Prepubertal melanoma has an incidence of 0.8 per million. Congenital melanocytic nevi
(CMN) are the most frequent predisposing factor to the prepubertal melanoma in cases where
a predisposition is detectable. The clinical and dermoscopic criteria leading to suspect
degeneration in the adult melanocytic nevi are less valid for CMN due to their frequent clinical
and dermoscopic variability over time. 520 children, 274 females and 246 males, with
CMN consecutively arrived to our observation and aged under 13 years – average age of 4.2
years – entered this prospective study. Between June 2005 and October 2011, the children
were monitored clinically and dermoscopically. In this population we found a fatal intracranial
melanosis, but no cutaneous melanoma. The data from this case study suggest that
1- infants with multiple (more than 3) CMN with a diameter greater than 3 cm and randomly
distributed throughout the skin surface and those with giant CMN should be investigated
for possible leptomeningeal melanosis; 2- parents must learn to caress the CMN to capture
the possible occurrence of nodules, which, especially if characterized by hard consistency,
must undergo a skin biopsy to rule out the suspicion of melanoma started from dermal component
of CMN; 3- it is not so far available in the literature, and the current series confirms
it, another clinical or dermoscopic criterion useful for early diagnosis of malignant transformation