A 58-year-old man develops parkinsonism poorly responsive to levodopa, along with early postural hypotension and urinary incontinence. Autopsy shows neuronal loss in the substantia nigra and olivopontocerebellar structures. Characteristic inclusions are found in which cell type?

• A Motor neurons, containing TDP-43 positive skein-like inclusions
• B Neurons of the substantia nigra, containing Lewy bodies
• C Astrocytes, containing tau positive tufted astrocytes
• D Oligodendrocytes, containing alpha-synuclein positive glial cytoplasmic inclusions ✓

Explanation

Multiple system atrophy combines parkinsonism, cerebellar ataxia, and autonomic failure. Its defining lesion is the glial cytoplasmic inclusion, an alpha-synuclein positive aggregate within oligodendrocytes, accompanied by neuronal loss in striatonigral and olivopontocerebellar systems. Lewy bodies are intraneuronal and define Parkinson disease and dementia with Lewy bodies. Tufted astrocytes are tau positive and characterize progressive supranuclear palsy, while skein-like TDP-43 inclusions occur in amyotrophic lateral sclerosis.

Reference: Robbins and Cotran Pathologic Basis of Disease, 10th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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