8762/1 Proliferative dermal lesion in congenital nevus


Definitions

Skin
ICD-O-3 topography code: C44

Proliferative nodules in congenital melanocytic naevi are defined as atypical
melanocytic proliferations that manifest predominantly in the neonatal period within a pre-existing large (giant/deep) congenital melanocytic naevus.
Histologically, epithelioid or spindled melanocytes are typically seen in the upper or mid dermis, within a large (giant/deep) congenital melanocytic nevus that involves the entire dermis and often extends into the subcutaneous tissue. The cells of the proliferative nodule appear to blend with the surrounding smaller melanocytes (nevus cells). Atypical nuclei and mitotic figures can be observed.
Clinically, the lesion typically presents as a dark plaque or nodule above a giant congenital melanocytic nevus. Proliferative nodules in congenital melanocytic nevi manifest predominantly in the neonatal period. The prognosis is favourable 1
 
LeBoit PE, Burg G, Weedon D, Sarasin A (Eds.)
World Health Organization Classification of Tumours. Pathology and Genetics of Skin Tumours
3rd Edition
IARC Press: Lyon 2005



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