26. Purulent meningitis

Staining: HE

Organ: Brain + meninges

Description:

Two types of tissue can be seen: eosinophilic brain parenchyme containing neurons and a basophilic exudate surrounding it.

The exudate contains many neutrophils. Some places the exudate “infiltrates” into the parenchyme slightly.

Diagnosis: Purulent meningitis

Theory:

While there are some places where the exudate appears to infiltrate into the brain parenchyme, it’s actually in the perivascular space and not inside the parenchyme. There is no inflammation of the brain, so no encephalitis. The inflammation is only of the meninges.

Overview of the slide

Close-up of the pus. Pus appears to be infiltrating into the parenchyme

Here you can see some places where the pus looks like it’s infiltrating into the parenchyme.