CNS Pathology Flashcards

Clinical involvement by CNS toxoplasmosis is seen in immunocompromised individuals, most notably in HIV+ patients, and involves usually cerebral cortex and deep gray matter nuclei. The infection reflects reemergence of latent disease acquired previously as a result of ingestion of infected food. The latent form is represented by slow-growing protozoa forms called bradyzoites encased in cysts with a cyst wall (arrows). Multiple basophilic dot-like parasites can be seen in cysts. A primary CNS infection may go unnoticed with this latent form and may never produce clinical symptoms

Active CNS disease is characterized by the presence of tachyzoites, which are free parasites in the tissue and which incite an inflammatory response. The cause of transformation of bradyzoite forms to tachyzoites during immunosuppression is not completely known. Tachyzoites are crescent-shaped 4-8 microns big organisms with a nucleus (arrow) that freely invade into the neuropil. This results in a mixed inflammatory reaction that may form large abscesses with ensuing focal CNS symptoms.

Clinical CNS involvement may be heralded by focal neurologic symptoms or non-specific symptoms such as fever, headache, and confusion. Brain MRI typically shows ring-enhancing lesions, which is characteristic but not diagnosis of this infection as similar lesions are seen in primary CNS large B-cell lymphoma, CNS tuberculosis, and CNS fungal infections. Toxoplasma cyst (arrow) shows a true cyst wall but may be mistaken for necrotic cell debris if not actively searched for. In active disease inflammatory cells may surround the cysts.
What’s on the differential for ring-enhancing CNS lesions?
The differential diagnosis of ring-enhancing CNS lesions with mass effect includes pyogenic brain abscess, syphilitic gummas, toxoplasmosis, TB, fungal infection, neurocysticercosis, gliomas, and lymphomas.

Arachnoidal cells in Arachnoid villi

Arachnoid granulations (dura peeled back)

Arachnoid, pia, subarachnoid space

Arachnoid villi

Aspergillus Hyphae in Blood vessels

Basal exudate - H. Influenzae (left)
Sonvexity exudate - S. Pneumoniae
What is the brown stuff?

Brown is normal lipofuschin due to aging

Cryptococcus neoformans (soap bubble appearance)

Cryptococcus neoformans (soap bubble appearance)

Cryptococcus neoformans (soap bubble appearance)

Cysticercosis

Cysticercosis
What is the organism?
How is it transmitted?

Cysticercosis
Taenia solium - larvae in pigs!

Cytoplasmic round Lewy inclusion
Is this early or late in abscess formation?

Early abscess
What are the labeled cells?

O - oligodendrocytes
N - neurons
A - astrocytes
Gray or white matter?

Gray matter - there is a neuron cell body, and the oligodendrocytes are surroundeing the cell body

Grocott silver stain - Aspergillosis

Herpetic encephalitis - temporal lobes affected
What type of virus?

HIV encephalitis - multinucleated giant cells



























































