OBJECTIVE: Kufs disease is the adult-onset form of neuronal ceroid lipofuscinosis (NCL). Its two clinical phenotypes are type A (progressive myoclonus epilepsy with dementia) and type B (behavioral abnormalities and dementia, associated with pyramidal and extrapyramidal signs). METHODS: We describe the clinical evolution of an atypical case characterized by progressive dementia and focal occipital seizures. RESULTS: A healthy 37-year-old woman began showing memory deficits and behavioral disturbances (apathy, lack of inhibitions, untidiness). After 4 years, she developed rare clusters of tonic-clonic seizures, as well as focal seizures originating from the temporo-occipital regions, clinically associated with visual hallucinations, wandering, and agitation. When she was 44 years old, neuropsychological assessment revealed severe frontotemporal dementia. MRI showed cortical atrophy and, on T2-weighted images, hypointensity of the basal ganglia, and hyperintensity and reduction of the deep white matter. On the basis of these findings, a diagnosis of Kufs disease was hypothesized. A skin biopsy was negative, but electron microscopy examination of a right frontal lobe brain biopsy revealed the presence of typical storage material (fingerprint inclusions). The patient never developed myoclonus or extrapyramidal signs. DISCUSSION: Kufs disease is difficult to diagnose on account of its heterogeneous clinical pattern and pathologic features, and the lack of a specific genetic locus alteration. The neuropsychological pattern and MRI findings observed in patients with early-onset frontotemporal dementia and seizure disorder suggest that Kufs disease should be considered in their differential diagnosis. Extracerebral biopsy can be nondiagnostic, and when alternative diagnoses have been ruled out, cerebral biopsy should be considered.