Stereotactic biopsy was performed. Postoperative head CT (not shown) showed no immediate complications.
Frozen section diagnosis:
Infiltrating glioma without necrosis or vascular proliferation on frozen section.
Final pathologic diagnosis:
Integrated diagnosis: astrocytoma, IDH-mutant, CNS WHO grade 4
Histologic diagnosis: astrocytoma with mitotic activity, necrosis, and microvascular proliferation
CNS WHO grade: 4
Molecular findings:
- IDH1/2: MUTANT [R132S] (PCR)
- ATRX: RETAINED nuclear staining (immunohistochemistry; consistent with
wild type) - p53: scattered weakly positive cells (immunohistochemistry; consistent
with wild type) - MGMT promoter methylation: NEGATIVE (PCR)
- 1p/19q: NOT co-deleted (FISH)
Note: The tumor demonstrates moderate cellular anaplasia, mitotic activity, focal necrosis with palisading and microvascular proliferation. The presence of retained nuclear staining for ATRX in the face of an astrocytic tumor with a mutation in IDH1 is unusual, and additional molecular studies might be informative about this finding.
NB: See the end of the case for subsequently amended final pathologic diagnosis.