Pilomyxoid Astrocytoma

Last updated on Wednesday, September 10 2008 by jdmiles

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Pilomyxoid Astrocytoma, Coronal sections through hypothalamus.
Pilomyxoid Astrocytoma appears to represent the evil step-sister of the benign pilocytic astrocytoma. Most pilomyxoid astrocytomas have been described in the hypothalamic region of very young patients.

Pilomyxoid Astrocytoma, H&E stain x 200
Pilomyxoid Astrocytomas resemble pilocytic astrocytomas except that the former does not contain solid areas with Rosenthal fibers, but instead demonstrates a diffusely myxoid matrix with a tendency toward perivascular rosetting (leading to its initial designation as an ependymal tumor).

Pilomyxoid Astrocytoma, Intraoperative smear preparation
The piloid nature of the tumor cells is readily apparent within this intraoperative cytologic preparation.

Pilomyxoid Astrocytoma, hypothalamic region, ventral surface of brain.
This aggressive variant of pilocytic astrocytoma group both exophytically and endophytically (as can be appreciated within the coronal section).

Pilomyxoid astrocytoma, H&E stain x 200
The pilomyxoid astrocytoma arises name from the hairlike astrocytes floating within a myxoid stroma.

Pilomyxoid astrocytoma, H&E stain x 400
Perivascular pseudo-rosettes with an appearance intermediate between that of astroblastomatous and ependymal type pseudo-rosettes are characteristically seen within pilomyxoid astrocytomas.