Neurocutaneous melanosis and temporal lobe tumor in a child: MR study.

The concept of neurocutaneous melanosis was described in 1948 by Van Bogaert [1] as a nonfamilial neuroectodermal dysplasia, but the first report of an individual with stigmata of neurocutaneous melanosis was made by Rokitansky [2] in 1861. The criteria to be met for diagnosis are large multiple pigmented skin nevi (more than 20 em in diameter) with an excess of melanotic cells in the leptomeninges, no malignant melanomatous transformation of the involved skin, and no evidence of malignant melanoma in any organ other than the nervous system. Until recently, diagnosis of involvement of the leptomeninges was impossible in vivo. MR imaging can be used now to diagnose such an involvement. The patient reported here is extremely unusual: He had typical skin involvement , but his intracerebral melanoma did not involve the leptomeninges. MR showed an unusual signal appearance, probably associated with the degree of enhancement of paramagnetic relaxation , that allowed us to diagnose a melanotic tumor even though the expected leptomeningeal involvement was absent.