Astrocytoma (mesial temporal)

Case contributed by A.Prof Frank Gaillard

Presentation

Seizure

Patient Data

Age: 60 years
MRI

An area of high signal on FLAIR within the left mesial temporal structures and extending along the body of the left hippocampus has positive mass effect. No contrast enhancement or elevated cerebral blood volume (CBV) is identified. Spectroscopy suggests decreased NAA and increased myoinositol. Right-sided mesial temporal structures are normal. Minor periventricular and subcortical white matter disease. No acute diffusion changes.

Conclusion: Infiltrative lesion with mass effect involving left mesial temporal structures and extending along the body of the left hippocampus, most likely representing a low-grade glioma. DDx paraneoplastic encephalitis. 

Pathology

The patient went on to have surgery.

Histology

MICROSCOPIC DESCRIPTION: Paraffin sections show fragments of a moderately hypercellular glial tumour involving cortex and white matter. Tumour cells have predominantly fibrillary astrocytic morphology with moderate nuclear and cellular pleomorphism. An occasional mitotic figure is identified. There is no microvascular proliferation and no necrosis is identified. A background population of morphologically unremarkable neurones is noted. No bi-nucleate forms are identified.

IMMUNOHISTOCHEMISTRY:

  • GFAP positive
  • Nestin negative
  • Nogo A positive in native oligodendrocytes
  • IDH-1 R132H negative (not mutated)
  • ATRX positive (not mutated)
  • MGMT negative (likely methylated)
  • p53 negative p16 CDKN2A positive
  • Topoisomerase labelling index: Approximately 5%.

FINAL DIAGNOSIS: IDH-1 R132H wild type diffuse astrocytoma (WHO Grade II).

Case Discussion

Mesial temporal lobe involvement has the differential of low grade glioma and paraneoplastic (limbic) encephalitis. If the patient is unwell and the onset is rapid then HSV encephalitis should also be considered. 

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Case information

rID: 49912
Case created: 9th Dec 2016
Last edited: 26th Jun 2017
Inclusion in quiz mode: Included

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