Lewy body

Lewy bodies are the inclusion bodies – abnormal aggregations of protein – that develop inside neurons affected by Parkinson's disease (PD), the Lewy body dementias (Parkinson's disease dementia and dementia with Lewy bodies (DLB)), and some other disorders. They are also seen in cases of multiple system atrophy, particularly the parkinsonian variant (MSA-P).

Lewy bodies appear as spherical masses in the cytoplasm that displace other cell components. For instance, some Lewy bodies tend to displace the nucleus to one side of the cell. There are two main kinds of Lewy bodies – classical and cortical. A classical Lewy body is an eosinophilic cytoplasmic inclusion consisting of a dense core surrounded by a halo of 10 nm wide radiating fibrils, the primary structural component of which is alpha-synuclein (α-synuclein). While similar in many other respects, cortical Lewy bodies are only faintly eosinophilic, do not have a surrounding halo, and do not show a radial filamentous substructure. Lewy bodies may be found in the midbrain (within the substantia nigra) or within the cortex.