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.[which?] They are also seen in cases of multiple system atrophy, particularly the parkinsonian variant (MSA-P).[1]
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.[2][better source needed] 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.[3] Lewy bodies may be found in the midbrain (within the substantia nigra) or within the cortex.