A 15-year-old girl died of a long-standing bulbar palsy that had caused difficult swallowing since early infancy. She was severely malnourished and retarded in growth. Morphologically, the clinical symptoms corresponded to a circumscribed lesion in the enlarged medulla (mega-medulla) that consisted of proliferation of astrocytes, incomplete demyelination, perivascular infiltrates and abundant formation of Rosenthal fibers. Rosenthal fibers were also present in the subpial medullary region where inflammation and astrocytic proliferation were largely absent. This patient's disorder appears to be a localized form of alexander's disease because macrencephaly, Rosenthal fiber formation and leukodystrophy of the cerebral hemispheres and cerebellum were absent. The morphological spectrum of Alexander's disease may now comprise diffuse and localized forms both of adulthood and children.