Central Nervous System
A stereotactic brain biopsy of a Progressive multifocal leukoencephalopathy (PML) patient reveals areas of demyelination. Which of the following histologic features is most likely to be present in this biopsy specimen? (LQ)
|A||Beta – A4 amyloid within blood vessels|
|B||Prion protein within extracellular plaques|
|C||Rosenthal fibers within astrocytes|
|D||Viral particles within oligodendrocytes|
a. Progressive multifocal leukoencephalopathy (PML) is a viral infection of oligodendrocytes that results in demyelination of the central nervous system.
b. Signs and symptoms of PML are varied but include dementia and ataxia along with abnormal vision and speech.
c. The causative agents of PML are two closely related polyomaviruses, JC virus and SV40.
d. 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 particles.
e. 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 arteries and arterioles in the brain and meninges of individuals with cerebral amyloid angiopathy (CAA), a significant cause of intracerebral hemorrhage in non hypertensive elderly patients.
f. Prion protein particles 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.