A case of diffuse cerebrospinal gliomatosis with extensive leptomeningeal spread is presented. The patient, an 18-year-old girl, was admitted due to progressive weakness and paresthesia of both legs, following rapid neuropsychiatric deterioration. An initial magnetic resonance imaging (MRI) study of the T-spine showed diffuse high signal intensities from T9 to T12 spinal cords on a T2 sagittal image and diffuse cord bulging at T1WI. This suggested an inflammatory lesion such as tuberculosis or fungal meningoencephalitis. A limited autopsy was performed. A microscopic examination revealed multifocal GFAP-positive astrocytic proliferations that were low grade astrocytoma in the cerebral leptomeninges, parietal, occipital and temporal lobes and anaplastic astrocytoma in the spinal cord and spinal leptomeninges. The high proliferative indices of the spinal lesion and aneuploidy correspond to a diagnosis of malignant astrocytoma and a rapid fatal clinical course.