Pilomyxoid astrocytoma

Case contributed by A.Prof Frank Gaillard

Presentation

Visual disturbance.

Patient Data

Age: 15 years
MRI

A sizable heterogeneously enhancing mass is centered on the hypothalamus and chiasm with some hydrocephalus. Features, especially in this age group, are of a hypothalamic-optochiasmatic glioma (pilocytic or pilomyxoid astrocytoma). 

Pathology

MICROSCOPIC DESCRIPTION:

An H&E stained section demonstrates a moderately cellular tumor composed of elongated oval to wavy nuclei set within a fibrillary and myxoid stroma. There are scattered thin-walled blood vessels present. No necrosis or microvascular proliferation is seen. There are no mitoses identified. The Alcian blue stain confirms myxomatous tumor stroma. (Histology courtesy of Prof. Michael Gonzales) 

Immunohistochemistry results show tumor cells stain:

  • IDHl - negative.
  • ATRX - positive.
  • P53 - negative.
  • H3K27M - negative.
  • H3K27ME3 - positive.
  • Topoisomerase proliferation index - 2-3%

FINAL DIAGNOSIS: Pilomyxoid astrocytoma (WHO grade I).

Case Discussion

Pilomyxoid astrocytomas and pilocytic astrocytomas are related but believed to be distinct. It is difficult to distinguish between them on imaging. 

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Case information

rID: 59455
Published: 11th Apr 2018
Last edited: 11th Apr 2018
Inclusion in quiz mode: Included

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