Multiple congenital melanocytic nevi in association with Dandy-Walker malformation

Abstract

Congenital melanocytic nevi (CMN) are benign pigmented lesions found in about 1% of all newborns or shortly after birth. Giant melanocytic nevi, with multifocal involvement, show significantly greater risk of developing malignant melanomas and neurocutaneous melanosis (NCM), particularly in a posterior axial location. NCM is a rare congenital disease characterized by multiple (≥3) small nevi, or at least one large congenital melanocytic nevus in combination with cerebral and/or leptomeningeal melanin deposits or melanoma. Dandy-Walker malformation (DWM) consists of a cystic dilatation of the fourth ventricle, hypoplasia or aplasia of the cerebellar vermis, and enlarged posterior fossa with or without hydrocephalus. The association of DWM and NCM has rarely been reported in the literature. A 3 month-old girl presented with increased head circumference and multiple various sized black plaques on her whole body. She underwent a ventriculoperitoneal shunt operation when she was 2 months-old. A skin biopsy was taken from the largest and darkest plaque of the trunk and showed hyperpigmentation of the basal layer of the epidermis. The dermis contained nevus cells in nests and sheets throughout the dermis, but no cellular atypia was noted. Magnetic resonance image (MRI) of the brain revealed severe hydrocephalus with hypoplasia of cerebellar vermis and agenesis of cerebellar tonsil which are consistent with Dandy-Walker malformation. We recommended a spinal MRI for check up the presence of leptomeningeal melanosis, but could not evaluate the result because of her being adapted. Herein, we present a rare case of multiple congenital melanocytic nevi in association with DWM in a neonate.