Progressive Multifocal Leukoencephalopathy (PML)
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Background Neuroimaging Gross Pathology Histopathology & Immunohistochemistry Differential Diagnosis Reference
BACKGROUND AND CLINICAL INFORMATION:
Usually seen in middle age person with disorders affecting the immune system, such as: AIDS, malignancy, TB, and sarcoidosis.
with AIDS have more severe symptoms. They usually die in less than 6 months.
Anatomic distribution of lesions: White matter of cerebrum, to a lesser extent, cerebellum, and brain stem.
is not known but is associated with JC virus infection. Characterized by
multifocal demyelination which grossly appear as gray foci in the white matter.
Lesions may also be found in the gray matter.
HISTOPATHOLOGY AND IMMUNOHISTOCHEMISTRY:
multiple foci of demyelination with enlarged and bizzare astrocytes, which
are often multinucletated and have multiple large processes. Lymphocytic
infiltration can also be seen.
or basophilic intranuclear inclusions are seen in atypical oligodendrocytes.
are found profusely in oligodendrocytes, rarely in astrocytes, and never in
is a prominent feature. However, destruction of axons, atypical for
demyelinating diseases, is also seen in PML.
necrosis with a phagocytic reaction indistinguishable from that seen in an
infarct may be seen at the center of the lesions.