Delayed Type of Acute Measles Encephalitis

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Background    Gross Pathology    Histopathology & Immunohistochemistry

BACKGROUND AND CLINICAL INFORMATION: Head

Other names: Immunosuppressive measles encephalitis, measles inclusion body encephalitis.

Pathogen: Rubeola virus (measles virus).

Clinical features:

• Contact with measles virus a few months before onset.

• Usually seen in immunosuppressed hosts but is also seen in normal children occasionally.

• Clinically, there is progressive deterioration with rapid progression to coma.  

• Usually fatal within a few weeks of onset.

Anatomic locations: Affects the cerebrum, brain stem, and cerebellum.

GROSS PATHOLOGY: Head  

The brain is grossly unremarkable.

HISTOPATHOLOGY AND IMMUNOHISTOCHEMISTRY: Head

Diagnostic feature: eosinophilic, usually intranuclear, inclusion bodies situated in neurons, oligodendrocytes or lying freely in the tissue. Immunohistochemistry is diagnostic. Viral particles can be seen in EM. (This is in contrast to many post-infectious encephalitis where only few viral particles are found).

Both gray matter and white matter are affected.

There may be no inflammatory cell infiltration and a lack of reactive astrocytes.

Not associated with demyelination.