Brain, Pick’s disease

Pick’s disease is a neurodegenerative disease classified as a frontotemporal lobar degeneration with abnormal intracellular accumulation of tau protein (i.e. a tauopathy). A unique feature of Pick’s disease is that the inclusions are of a particular isoform (splice variant) of tau known as 3-repeat tau. Clinically, it typically presents as behavioural variant frontotemporal dementia or with predominantly language symptoms. Gross examination of the brain usually shows severe “knife-edge” atrophy mainly affecting frontal and temporal lobes. Microscopically, there is severe neuron loss and gliosis in the affected cortical areas, which can lead to a spongiotic appearance. Neurons contain characteristic discrete round basophilic cytoplasmic inclusions (Pick bodies), which are especially prominent in the granule cell layer of the dentate gyrus. Some neurons have a ballooned appearance (Pick cells). Both are positive for tau immunohistochemistry and on Bielschowsky silver stain but are characteristically negative on Gallyas silver stain due to their 3-repeat tau composition (see Related Content). Patients on average live 12 years after diagnosis.