the authors report a case of neuronal ceroid lipofuscinosis kufs disease confirmed by stereotactically obtained brain biopsy findings and initially diagnosed as a butterfly glioma the presenting symptoms in the 64 year old patient were mental alterations with progressive dementia followed by muscular atrophy and myoclonia with distal preponderance the mild initial disturbances of coordination increased and the patient developed a markedly ataxic gait computerized tomography ct scanning and magnetic resonance imaging revealed generalized cerebral atrophy and a bifrontal space occupying lesion involving the callosum the original clearcut diagnosis of glioblastoma multiforme based on ct scans was unexpectedly disproved by examination of stereotactically obtained brain biopsy specimens which revealed a neuronal ceroid lipofuscinosis kufs disease to the authors knowledge this is the first report of a case presenting with both diffuse brain atrophy and localized accumulation of neuronal lipofuscin mimicking a mass lesion on radiological studies.