MRI Features of Leptomeningeal Melanosis

Neurocutaneous melanosis (NCM) is a rare congenital dysmorphogenesis characterized by large or multiple congenital benign melanocytic nevi and diffuse or local leptomeningal involvement of abnormal pigmentation. Intracranial lesions may occur in the leptomeninges and cerebral parenchyma. The clinical presentations are nonspecific, and the prognosis is extremely poor for symptomatic patients, even in the absence of malignant melanoma. At present, the best imaging method for diagnosing leptomeningeal melanosis (LMM) is magnetic resonance imaging (MRI), and the T1-weighted images are the best to demonstrate the features of NCM in the central nervous system. We describe the MRI features of LMM in a case of NCM.