Diffuse low grade astrocytoma (grade II) with intraventricular extension.

Discussion:

Partial resection of the tumor was performed.

MICROSCOPIC DESCRIPTION:

The sections show features of a moderately cellular astrocytic tumor. The tumor cells have slightly elongated and hyperchromatic nuclei with a microcystic background. 2 mitoses are seen within the entire tumor. No microvascular proliferation is present. One hypocellular fragment is necrotic, which may be related to previous surgery, rather than being tumor cell necrosis.

Immunohistochemistry:

  • p53 positive
  • IDH1-R132H immunostain is positive
  • MGMT is negative (likely methylated)
  • ATRX shows loss of staining (mutated)
  • the topoisomerase index is about 2%

DIAGNOSIS:

Diffuse astrocytoma, IDH-mutant, ATRX-mutant (WHO Grade II).

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