This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Surgery
[{'content': 'A 42-yrs-old immunosuppressed male presents with rapidly progressed neurologic symptoms including mental deterioration, visual loss, abnormal speech, and ataxia, Radiographic studies demonstrate multifiocal lesions in the white matter without mass effect. A stereotactic brain biopsy reveals areas of demyelination. Which histologic feature is most likely to be present in this? \nSelect and explain. \nA. Beta-A4 amyloid within blood vessels, B. Prion protein within extracellular plaques, C. Rosenthal fibers within astrocytes, D. Viral paicles within oligodendrocytes', 'role': 'user'}, {'content': 'Answer: D \nExplanation: * Progressive multifocal leukoencephalopathy (PML) is a viral infection of oligodendrocytes that results in demyelination of the central nervous system. * Signs and symptoms of PML are varied but include dementia and ataxia along with abnormal vision and speech. The causative agents of PML are two closely related polyomaviruses, JC virus and SV40. * The pathognomonic feature of PML is the oligodendrocytes in areas of demyelination, which have a "ground-glass\' appearance of their nuclei due to infection with the viral paicles. * PML occurs as a terminal complication in immuno suppressed individuals, especially individuals with AIDS. In contrast to the viral inclusions of PML, beta-A4 amyloid is found in the walls of medium to small aeries an aerioles in the brain and meninges of individuals with cerebral amyloid angiopathy (CAA) , a significant cause of intracerebral hemorrhage in non hypeensive elderly patients. * Prion protein paicles are causes of the spongiform encephalopathies, while Rosenthal fibers within astrocytes are characteristic of juvenile pilocytic astrocytomas, and ubiquitin protein within neurons is associated with Alzheimer\'s disease.', 'role': 'assistant'}]