NQ-121a: (B) This is most likely a non-neoplastic cell

NQ-121b: (A) Cryptococcosis

Diagnosis: Cryptococcosis

 

Reactive gliosis: The cell highlighted by the black arrow is a reactive astrocyte there are a couple more in this image. This is not a neoplastic cells. Ependymal cells do not give this type of star like morphology. It reflective reactive changes to, usually, a non-neoplastic process but can also be seen in some non-neoplastic process.

 

The cell being highlighted by the black arrow has a shape reminiscent of a star and these are reactive gliosis also known as astrocytosis. Literally, astro- means stars. Reactive glia or reactive astrocytes from the pathologic point of view refer to morphological of astrocytes into a prominent star shape when the brain is responding to injury, ischemia, and pathologic processes.  The fluid in craniopharyngioma is believed to be highly irritable as reflected by the intense gliosis in these cystic walls. Rosenthal materials are often found in these areas. There are also functional changes in status of these cells but such functional changes are difficult to be measured base on histologic methods.

Most glial neoplasms are not associated with substantial amount of reactive gliosis. The presence of substantial number of reactive glial cells raise the possibility of a non-neoplastic process such as reactive to location irritation, repair of trauma,demyelinating process, ischemia and infarction, viral infections, and other situations. One of the best examples of exuberant reactive gliosis is gliosis around the cystic component of a craniopharyngioma. In addition, neoplastic changes not of the glial lineage (astrocytoma, oligodendroglioma, ependymoma, glioblastoma, and et cetera) can and often associate with a good number of reactive astrocytes. One of the best example is diffuse large B-cell lymphoma.

 

Reference:

• Pekny M, Pekna M. Reactive gliosis in the pathogenesis of CNS diseases. Biochim Biophys Acta. 2016 Mar;1862(3):483-91.

Pathology of the case: In this particular case, the Cryptococcus in yeast form is not stained and appears as a negative image among the cytoplasm stained by the Diff-Quick (white arrows). One should note that the yeast appears as small bright dots on low magnification which can be easily dismissed as entrapped air bubbles (white arrow in the image with low magnification). On hematoxylin and eosin stain, Cryptococcus often appears as perfectly circular transparent discs that do not take up stain. But their presence is best demonstrated by the use of special stains such as PAS and GMS. In particular, the mucopolysaccharide outer coat of Cryptococcus is positive for mucicarmine stain. [Click here to see cryptococcus on special stains]

PML and diffuse large B-cell lymphoma: Although these two entities can be seen in HIV(+) patients and often have reactive gliosis on cytologic preparations and histologic sections, the presence of these clear perfectly round discs are indicative of the presence of Cryptococcus. There are no atypical cells present to suggest either PML or diffuse large B-cell lymphoma.

Toxoplasmosis: This is another condition that is often, but not always, associated with immune compromised patients. The histologic diagnosis is by identification of the toxoplasma cyst in histologic section. [Click here to see an image of toxoplasmosis]

Coccidioides immitis: This fungus is native to the San Joaquin Valley of California. Together with  Coccidioides posadasii which is endemic to certain arid-to-semiarid areas of the southwestern United States they are the two most commonly seen organisms that cause coccidioidomycosis in the United States. Coccidioidomycosis is usually transmitted by inhalation of airborne spores. In contrast to other conditions being mentioned in this quiz, Coccidioidomycosis is not associated with compromised immunity. Histologically, the fungus is large, ranging from 10 to 80 μm in size, and contains numbers spherules with thick, refractile wall. They can often be recognized on hematoxylin and eosin stain without special stain but, like other fungal organisms, they are well demonstrated by GMS and PAS stain. [Click here to see an image of coccidioidomycosis on HE stain]