[Melanocytosis neurocutanea].

An 11-month-old girl with a large "swimming-suit" neavus whose head began to enlarge at the age of 3 months was subdued to sonographic and computer tomographic examinations. The latter revealed a complete obstructive hydrocephalus of all brain ventricles. The section and histologic examinations indicated that the obstruction was caused by extensive melanocytosis of leptomeninges at the cerebellar base, pons and spinal cord thus blocking out the outlets of the IVth brain ventricle. (Fig. 8, Ref. 8.).