Pilocytic astrocytoma - Squash preparation

Pilocytic Astrocytoma:

• Most common astrocytoma in children.

• Most common sites: Cerebellum, Floor of 3rd ventricle, thalamus, hypothalamus.

Most striking feature: Hair like (pilocytic processes) seen in the background.

Cells are monomorphic (uniform in size and shape) with ovoid bipolar bland appearing nuclei.
Many Rosenthal fibres and Eosinophilic Granular Bodies will be seen.

Rosenthal Fibres:

• Brightly eosinophilic, thick, glassy cork-screw shaped/ carrot shaped srtuctures.

Eosinophilic Granular Bodies:

• Brightly eosinophilic granular clumps/ globoid deposits.

For those of you who are still thinking about "What a squash preparation is?"

• In squash preparation, a small piece of tissue is placed on one end of a slide. Another slide, right angles to the first slide is used to compress, squash and spread the tissue (length wise) over the first slide.
• It is then fixed, stained and examined under a microscope.
• Used in the intra-operative diagnosis of brain tumours.