Diffuse Leptomeningeal Hyperintensity on Fluid-Attenuated Inversion Recovery MR Images in Neurocutaneous Melanosis

Neurocutaneous melanosis (NCM) is a rare neuroectodermal dysplasia characterized by large or multiple cutaneous congenital pigmented nevi and benign or malignant melanocytic tumors of the leptomeninges. Although the MR manifestations of this disease have been reported in a small series of cases, the usefulness of fluid-attenuated inversion recovery (FLAIR) MR findings has not been documented. We present a case of NCM that showed diffuse leptomeningeal hyperintensity on FLAIR images. This FLAIR finding may be a clue to the detection of leptomeningeal abnormalities in NCM.