The patient went on to have a stereotactic biopsy.

Histology

Paraffin sections show cores of a densely cellular glial tumor. Tumor cells have fibn'llary astrocytic morphology, show moderate nuclear and cellular pleomorphism and are arranged in diffuse sheets. Moderate numbers of mitotic figures are identified (5 in 10 HPF). There is no multilayering of atypical cells around vessel Iumena and no necrosis is identified.

IMMUNOHISTOCHEMISTRY:

• GFAP positive
• Nogo A positive in native oligodendrocytes
• IDH-1 R132H negative (not mutated)
• ATRX positive (not mutated)
• P53 positive
• P16 CDKNZA negative
• Topoisomerase labeling index: Approximately 15%.

FINAL DIAGNOSIS: Anaplastic astrocytoma, IDH wild-type (WHO Grade III).