Reactive astrocytes, Diff-Quick stained smear: These cells are reactive astrocytes (arrow) and look like a star, the reason why they are called astrocytes, or you can say that they look like a swimming octopus! Although neoplastic astrocytes can look stellate, they are rarely this dramatic.
Cryptococcus, Diff-Quick stain stained smear: The reactive astrocytes and their cytoplasmic processes take up the stain but not the Cryptococcus. The stained background in this particular image plays the role of Indian ink for demonstration of a negative image of the cryptococcus (arrow).
Cryptococcus, HE section:
The round almost empty spaces represent the non-viable
Cryptococcus (arrow). Although they can be well-demonstrated by PAS stain and GMS stain,
they essentially appear as an negative image against the stained background.