Discovered by Frederic Lewy in 1912, Lewy Bodies are cytoplasmic eosinophilic masses made up of alpha synuclein and other proteins (like neurofilament protein & alpha-B crystalline) that develop inside nerve cells in Parkinson’s disease (PD), Lewy Body Dementiaand some other disorders. They are identified under the microscope when biopsies are performed on the brain.
Lewy bodies appear as spherical masses that displace other cell components. There are two morphological types:
- Classical (brain stem) Lewy bodies: It is an eosinophilic cytoplasmic inclusion that consists of a dense core surrounded by a halo of 10-nm wide radiating fibrils, the primary structural component of which is alpha-synuclein
- Cortical Lewy bodies: It is less well defined & lacks the halo. However, it is still made up of alpha-synuclein fibrils. They are a distinguishing feature of Dementia with Lewy bodies (DLB) and may occasionally be seen in Pick’s disease, corticobasal degeneration, tauopathies and multiple system atrophy of the Parkinsonian variant.
The brain of the patients presents with atrophy and the microscopic findings include neuronal loss, astrocytosis. The cortex and basal ganglia are most commonly affected. Grey matter is affected early and lesions are more severe.