Epidermal nevus syndrome with hemimegalencephaly: neuropathological study.

A neuropathologic examination of a 5-year-boy with epidermal nevus syndrome and hemimegalencephaly revealed 1) left hemimegalencephaly with an increased volume of the white matter, and 2) cerebral polymicrogyria with pachygyria, heterotopic neurons and prominent astrogliosis. Golgi staining revealed hypertrophic neurons with increased dendrites and spines. The hemihypertrophy of the cerebral hemispheres seems to have contributed to an increased volume of the white matter with migration disorder, and may have been due to a disorder in the germinal cell proliferation stage.