Dementia with Grains: A Clinical Mimic of Dementia with Lewy Bodies - Case Report.

Introduction: Dementia characterized by the accumulation of argyrophilic grains (AGs) in neurons as sole neuropathology at autopsy is known as dementia with grains (DG). The clinical features of DG include progressive memory disturbances and behavioral changes. Recently however, cases of DG presenting with parkinsonism were also described. Here, we report the first case of DG mimicking dementia with Lewy bodies. Case Presentation: A 72-year-old male patient was seen at our outpatient memory clinic with progressive complaints in multiple cognitive domains (memory, orientation, praxis, and executive function), fluctuations in arousal and behavioral changes. In addition, he reported neuropsychiatric symptoms, including a depressed mood and visual hallucinations. During neurological examination, he demonstrated bilateral rigidity and bradykinesia with a right-sided predominance. These symptoms in combination with decreased striatal uptake of tracer on a 123I-FP-CIT-SPECT scan led to the clinical diagnosis of probable mild dementia with Lewy bodies. Treatment was with rivastigmine, and levodopa/benserazide was initiated. Over the years, cognitive and motor function only slowly progressed. Autopsy was performed after passing. Neuropathological findings included dot-like and comma-shaped tau-positive structures, indicative of AGs, spread throughout the limbic but also the nigrostriatal system. No co-pathology and in particular no alpha-synucleinopathy was present. Consequently, patient's diagnosis was posthumously revised to DG. Conclusion: Here, we present the first known case of DG clinically mimicking dementia with Lewy bodies. Our findings support the notion that parkinsonism should be included in the clinical phenotype of DG and that DG should be considered more often as diagnosis, when the clinical presentation is atypical.