Diffuse astrocytoma IDH-mutant - gemistocytic

Case contributed by Royal Melbourne Hospital

Presentation

Difficulty at work, with recent development of headache.

Patient Data

Age: 40 years
Gender: Male

Pre and post contrast CT demonstrate a large right frontal lobe mass, mostly cystic with small irregular areas of peripheral enhancement. Significant local mass effect with subfalcine herniation is present with obstruction to CSF outflow from the left lateral ventricle. 

An intra-axial mixed cystic solid tumor centered in the right frontal pole measuring 7.7 cm in maximum diameter is demonstrated. A macrocystic component extends into the right frontal horn and abuts the septum pellucidum. Multiple smaller cysts embeded in a solid component involves the right rectus gyrus cortex.

Multiple septae and a thick cord of enhancement are detected. The mass causes subfalcine herniation with midline shift to the left of 1.6 cm. The anterior cerebral arteries abut the lesion and are displaced to the left. Left temporal horn dilatation keeping with obstruction at the level of the foramen of Munro. The third ventricle is effaced.

There is surrounding edema.No diffusion restriction detected within the mass lesion. No remodeling of the overlying skull.No susceptibility artefact to suggest calcification or blood products.

Histology was obtained following craniotomy and macroscopic resection. 

Histology

Pathology

MICROSCOPIC DESCRIPTION: Paraffin sections show a densely hypercellular astrocytic glioma composed predominantly of gemistocytic cells with a quantitatively smaller component of fibrillary astrocytes.  Tumor cells show moderate nuclear and cellular pleomorphism.  An occasional mitotic figure is identified.  No vascular endothelial cell hyperplasia is seen and there is no necrosis.  Tumor extends through the full thickness of cerebral cortex.  Prominent perivascular cuffing by small lymphoid cells is noted throughout the tumor.

Immunohistochemistry shows moderate staining in tumor cells for IDH-1. The topoisomerase labeling index is approximately 2% (not shown).

DIAGNOSIS: Right frontal brain tumor:  Gemistocytic astrocytoma (WHO grade II)

Case Discussion

Gemistocytic astrocytomas, although currently still considered a WHO II tumor have a poorer prognosis than other WHO II astrocytomas

Case courtesy of A. Prof. Frank Gaillard. Histology courtesy of A. Prof. Michael Gonzales. 

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