Glioblastoma (IDH-1 negative)

Case contributed by A.Prof Frank Gaillard

Presentation

3 generalized tonic clonic seizures

Patient Data

Age: 25 years
Gender: Male
Modality: MRI

Selected FLAIR and T1 C+ images demonstrate a small region of high T2 involving the cortex and subcortical white matter of the precuneus, without contrast enhancement. This was felt to most likely be a low grade glioma, or potentially a region of focal cortical dysplasia. Follow-up imaging was organised. 

4 months later

Modality: MRI

Selected FLAIR and T1 C+ images demonstrate surprisingly fast growth with faint punctate enhancement now visible. Findings are suspicious for progression to a higher grade.

The patient was reviewed as an outpatient a few weeks later. Given the fairly rapid growth, the decision was made to biopsy this lesion and a stereotaxis scan was organised. 

1 month later still

Modality: MRI

Selected FLAIR and T1 C+ images from stereotaxis scans for operative planning demonstrate still further growth and increase in enhancement. 

Modality: Pathology

MICROSCOPIC DESCRIPTION:

Paraffin sections show multiple fragments of a densely  hypercellular tumour. Tumour cells have pleomorphic round, oval and  angulated hyperchromatic nuclei with fibrillary processes. Moderate  numbers of mitotic figures are identified (8 in 20 high power  fields). Foci of microvascular proliferation with multilayering of  atypical cells around vessel lumena are noted and there are scattered  foci of palisaded necrosis. There is patchy microcalcification.

IMMUNOHISTOCHEMISTRY:

  • GFAP: positive
  • Nestin: positive (high)
  • IDH-1 R132H: negative (not mutated)
  • ATRX: positive (not mutated)
  • p53: positive
  • p16 CDKN2A: positive
  • MGMT: positive (likely unmethylated)

Topoisomerase labelling index:  Approximately 40%.

DIAGNOSIS: Glioblastoma (WHO Grade IV)

Case Discussion

This case illustrates the difficulty conventional imaging has in distinguishing a low grade tumour with indolent biological behaviour from early imaging of a more aggressive tumour. In this case were a biopsy to have been performed at the time of the first scan it would almost certainly have demonstrated a diffuse low grade glioma. At that stage however it would have been IDH-1 negative, which would have been predictive of aggressive behaviour. 

The importance of IDH-1 status is going to be reflected in the soon to be published 2016 WHO CNS classification. 

 

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Case Information

rID: 43877
Case created: 27th Mar 2016
Last edited: 27th Mar 2016
Inclusion in quiz mode: Excluded

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