The patient went on to have surgery.

Histology

MICROSCOPIC DESCRIPTION:

Sections show a moderately cellular tumor composed of moderately pleomorphic cells containing round to oval, hyperchromatic, vesicular nuclei with inconspicuous nucleoli. Tumor cells are arranged in diffuse sheets with a "protoplasmic" morphology. No mitotic figures are identified. No necrosis or microvascular proliferation are seen.

IMMUNOHISTOCHEMISTRY:

• GFAP Positive
• Nogo A Positive
• Nestin Positive (intermediate)
• IDH-1 R132H Positive (mutated)
• ATRX Equivocal
• MGMT Negative (likely methylated)
• p53 Equivocal
• p16 Negative
• Topoisomerase labeling index: Approximately 1-2%. 

FISH For Chromosome 1p/19q Deletion: No 1p/19q loss detected.

FINAL DIAGNOSIS: Diffuse astrocytoma, IDH-1 mutant (WHO Grade II).

This case is typical of the entity previously known as protoplasmic astrocytoma, which is no longer recognized as a distinct entity in the current (2016) WHO classification of CNS tumors. This is a shame as it is a recognizable tumor and is probably highly predictive of intact 1p19q status.