
There are pathology rooms with multi-headed microscopes: 8-10 viewing stations connected to a single slide mount so everyone is viewing the same slide simultaneously. A pathologist usually "drives" and physician and fellows (and me!) sit around the other viewers. The pathologist loaded in stained, prepared slides of the brainstem, cerebellum, and cortex for examination.
Slide #1 cerebellum. The cerebellar cortex is made up of three layers: the mol

In the parenchyma we noted neuronophagia: dying neurons surrounded by microglial cells. This pointed us towards considering a viral diagnosis. Bacteria can stay in the meninges surrounding the brain, but viruses are obligate cellular parasites and thus more likely to appear in the neural tissue itself. We examined the neurons for inclusion bodies, which are accumlations (not exclusive to viral infections) within either the cytoplasm (ex rabies) or nucleus (ex. herpes). Not all viral infections have inclusion bodies, but their presence, absence and type can help to identify the specific pathogen. In this patient there were no inclusion bodies.

Slide #3: midbrain (brainstem). The substantia nigra in the midbrain was noted to be unpigmented. This area usually develops pigment between 3-5 years of age (and can be lost again in old age as part of a neurodegenerative process). This placed the patient's age between 12 months and 3 years.
Slide #4: spinal cord. Most infections have a regional preference within the nervous system; they don't invade all areas equally. Thus, looking at which regions are affected can narrow down the pathogens under consideration. In our patient, the anterior horn of the spinal cord was disproportionately infected, which led us to consider the enteroviruses (ex polio, Hep A).
Note: this case has been previously published so the details have not been altered. All photos used are from searching google images and are not the slides from the actual conference.
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