1. Lateral view of Pick's disease brain
Pick's disease is a rare neurodegenerative disorder, occurring approximately one-tenth as often as Alzheimer's disease. Clinical differentiation from Alzheimer's disease can be difficult, although early in the course of the disease process personality problems are more common in Pick's disease, while memory problems are more common in Alzheimer's disease.
Pathologically, there is "lobar atrophy" involving the frontal and temporal lobes, with sparing of the occipital and parietal lobes (Figure1). In addition, the posterior two-thirds of the superior temporal gyrus (that part behind the precentral gyrus) is spared. The cerebral gyral atrophy in Pick's disease is so severe that some of the gyri are extremely thin (termed "knife blade atrophy").
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1. Lateral view of Pick's disease brain |
There is a marked loss of the small granular neurons in the dentate gyrus of the hippocampal formation, while the dentate gyrus is preserved in Alzheimer's disease and other neurodegenerative disorders (Figure 2). The characteristic histologic change in Pick's disease is the presence of spherical inclusions called Pick bodies in neurons of the cerebral cortex, basal ganglia, and brainstem. Although Pick bodies can be can be seen in microscopic sections stained with hematoxylin and eosin (H&E), they are most readily visualized in sections stained with silver impregnation techniques (e.g., Bielschowsky stain or Bodian stain; Figure 3).
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2. Dentate fascia in Alzheimer's disease (top) and Pick's disease (bottom) |
3. Arrows show one of several Pick bodies in H&E-stained (top) and silver-stained sections (bottom) |