Neurocutaneous melanosis associated with inferior vermian hypoplasia: Mr findings

Objective: We describe the MR findings of two cases of neurocutaneous melanosis (NCM) associated with inferior vermian hypoplasia (IVH). Materials and Methods: Two cases of NCM associated with IVH are pre-sented. Both patients had congenital giant hairy nevi and multiple satellite lesions. Results: Magnetic resonance imaging revealed IVH as well as hyperintensities in the pons and the cerebellar leptomeninges on Tl-weighted images. The hyperintensities may be ascribed to the Tl-shortening effect of melanin. A right parietal tumor in one patient and unilateral ventriculomegaly in another patient were also depicted. Conclusions: Magnetic resonance demonstration of the Tl-shortening lepto- meningeal infiltrations adds weight to the diagnosis of NCM. The implication of the concurrence of NCM and IVH is discussed.