The question highlights two critical pathological features associated with a progressive nervous system disease: degeneration of neurons and the presence of specific cellular structures called cytoplasmic inclusion bodies, explicitly named Lewy bodies.
Lewy bodies are abnormal accumulations of protein that disrupt normal brain function. Their identification within degenerating neurons is a key diagnostic hallmark.
Specifically, the combination of neuronal degeneration and the presence of Lewy bodies is pathognomonic for Parkinson's Disease. This pathology is central to the development of the characteristic motor symptoms seen in Parkinson's patients.