| A large or giant congenital melanocytic nevus (LCMN or GCMN) is a pigmented skin lesion of more than 20 cm - or 40 cm- respectively, projected adult diameter, composed of melanocytes and presenting with an elevated risk of malignant transformation. An LCMN is a darkly colored, circumscribed area of the skin sometimes covered with dense hair or proliferative nodules, and/or accompanied by multiple small satellite nevi that develop at birth or during early childhood (tardive satellites). Patients with LCMN also present an elevated risk of malignant pediatric melanoma, particularly intracranial, and other neuroectodermal tumors of varying severity. LCMN is a neurocristopathy (a disorder of the development of the embryonic neural crest) but its etiology is unknown. Familial cases have been observed, but the vast majority of LCMN cases are sporadic. |
