Purpose or Case Report: Melanocytic nevi which present either at birth or soon after are known as congenital melanocytic nevi. Neurocutaneous melanosis is a rare sporadic phakomatosis caused by pigment cell tumours of the leptomeninges; These can be seen in association with giant congenital melanocytic nevi. Unfortunately, giant congenital melanocytic nevi with neurocutaneous melanosis has a poor prognosis.

This pictorial review aims to present and describe the imaging features on MRI and CT of children with melanocytic nevi and neurocutaneous melanosis. These changes affect both the brain and the spine.

Methods & Materials: Imaging of children from our institution with congenital melanocytic nevi are shown. These demonstrate the salient imaging features, including intraparenchymal melanosis with focal T1 signal hyperintensities involving the mesial temporal lobes, amygdala, pons, medulla and cerebellum. Extensive leptomeningeal disease is also a common finding, which can result in hydrocephalus. Other features include arachnoid cysts. Associations include Dandy-Walker malformations.

Results: Relevant imaging features are shown and explained.

Conclusions: Congenital melanocytic nevi syndrome with neurocutaneous melanosis is a rare sporadic phakomatosis, which has characteristic imaging features. These imaging features are demonstrated and explained to assist pediatric radiologists with understanding and reporting these rare cases.