Microscopic description and IHC:

The post-mortem hippocampus brain section shows diffuse plaque and neurofibrillary tangle formation. The immunohistochemical stains highlight the ß-amyloid plaques and the tau-positive neurofibrillary tangles.

Discussion:

The progression of Alzheimer’s disease can be correlated with the location of the ß-amyloid plaques in the brain. The plaques are initially seen exclusively in the neocortex, followed by allocortical areas. The third phase involves diencephalic nuclei, the striatum, and cholinergic nuclei in the basal forebrain. Next, the brainstem becomes involved, and finally in phase 5, the cerebellum displays ß-amyloid deposition.

Using this aforementioned distribution, a frequency score of neuritic plaques called the CERAD score, and a neurofibrillary tangle score (called the Braak and Braak score and also based on location), one can reliably diagnose Alzheimer’s disease and correlate it with a clinical impression of the patient.

References:

Hyman et al. National Institute on Aging-Alzheimer’s Association guidelines for the neuropathologic assessment of Alzheimer’s disease. Alzheimer’s & Dementia 2012; 8:1-13.

Thal et al. Phases of Abeta-deposition in the human brain and its relevance for the development of AD. Neurology 2002; 58:1791-1800.

Braak H and Braak E. Staging of Alzheimer’s Disease-Related Neurofibrillary Changes. Neurobiology of Aging 1995; 16 (3): 271-284.

Mirra et al. The Consortium to Establish a Registry for Alzheimer’s disease (CERAD). Part II Standardization of the neuropathologic assessment of Alzheimer’s disease. Neurology 1991; 41:479-486.

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