Glioblastoma IDH wild-type (thalamic with pseudoprogression)

Case contributed by A.Prof Frank Gaillard

Presentation

Seizures.

Patient Data

Age: 55 years

Summary

Modality: Annotated image

Summary T1 C+ and FLAIR images showing typical evolution of treatment effects gradually subsiding over 18 months. This of course does not mean that there is no tumour, and in fact some tumour progression is evident on the last slide posteriorly. 

Initial MRI

Modality: MRI

A well circumscribed thalamic high T2 lesion with positive mass-effect is noted. It demonstrates no enhancement and facilitated diffusion.  A small right cingulate cortical region of increased T2 signal is also noted. 

Right thalamus mass is again demonstrated, increased in size. A new focus of FLAIR hyperintensity projects from the right anterolateral surface of the tumour into the genu and anterior limb right internal capsule and there is new extension superiorly into the posterior body of the corpus callosum. Foci of ring enhancement within the right thalamic lesion are now evident with marked elevation cerebral blood volume (not shown). MR spectroscopy in the right thalamic tumour demonstrates marked elevation of choline and reduced NAA. No convincing lactate peak is demonstrated (not shown).

The patient went on to have a biopsy.

Histology

MICROSCOPIC DESCRIPTION:

Sections show a hypercellular tumour composed of sheets and rosette-like structures. There is focal microvascular proliferation and pallisaded tumour cell necrosis. Tumour cells contain fibrillary eosinophilic cytoplasm, pleomorphic hyperchromatic nuclei with intranuclear cytoplasmic inclusions and inconspicuous nucleoli. Numerous large, multinucleated tumour cells with prominent intranuclear cytoplasmic inclusions are present. Frequent mitoses are observed (up to 12 per 10hpf).

Immunohistochemical results:

  • GFAP Positive ​
  • Nestin Positive (high)
  • IDH-1 R132H Negative (not mutated)
  • ATRX Positive (not mutated)
  • MGMT Negative (likely methylated)
  • p53 Positive (strong)
  • p16 CDKN2A Positive
  • Topoisomerase labelling index: Approximately 30%.

FINAL DIAGNOSIS: IDH-1 wild-type (negative) gigantocellular glioblastoma, WHO grade IV.

Treatment

The patient was commenced on Stupp protocol (chemotherapy and radiotherapy). 

5 months - end of radiotherapy

Modality: MRI

The right thalamic lesion has progressively increased in size since the first exam with heterogeneous high signal on T2 with necrotic components that suppress on FLAIR and heterogeneously enhances after contrast administration. Most of the apparent elevation of cerebral blood volume (CBV) is due to vessels coursing on the surface of the circumscribed enhancing mass, with minor persistent elevation at the inferior aspect of the mass. Most of the enhancing component has low CBV. The high T2/FLAIR surrounding signal abnormalities are now extending further through the anterior basal ganglia and deep white matter anteriorly, these areas demonstrates minor choline elevation on spectroscopy.

Conclusion:

Most of the changes in appearance of the thalamic mass are attributable to treatment effect with increase in size and FLAIR change probably representing pseudoprogression, especially in the setting of MGMT methylation.

11 months

Modality: MRI

There has been slight increase in size of the FLAIR hyperintense mass centred at the right basal thalamus, with moderate increased surrounding FLAIR hyperintensity along the right frontal white matter and mild increased local mass effect. The thin peripheral ring enhancement with fine internal enhancing septations and nodules is similar to prior MRI, but has changed from the earlier more central nodular enhancement.

The increased CBV centrally within the lesion is no longer present and is currently prominently low.

Conclusion:

Most of the changes are still most likely to be treatment related.

14 months

Modality: MRI

The right thalamic rim-enhancing lesion has reduced in overall size. There is a stable degree of surrounding T2 FLAIR hyperintensity in the right frontal, temporal and parietal lobes. No suspicious change in CBV. The central portion of the lesion shows heterogeneous signal particularly on T2, incompletely suppresses on FLAIR, is non-enhancing, with increased susceptibility. MR spectroscopy shows marginally elevated choline in some of the enhancing components, with mild NAA suppression. The central portions of the tumour show elevated lipid/lactate, indicating necrotic material.

Conclusion:

Reduced overall size of the enhancing right thalamic lesion, in keeping with treatment related change.

18 months

Modality: MRI

Compared to the previous MRI, the size of the new irregularly shaped ring enhancing lesion at the right thalamus/globus pallidus has decreased in size, although this area still demonstrates increased CBV (note area is susceptibility affected). In addition, a more solidly enhancing lesion has developed immediately posteriorly, in the posterior right thalamus with elevated CBV and mild rim diffusion restriction, and associated increased extent of FLAIR hyperintensity with a mild increase in mass-effect.

Spectroscopy again demonstrates regions of elevated choline and lactate. 

Case Discussion

Pseudoprogression is typically encountered in the first 6 months following completion of radiotherapy and is particularly common in MGMT methylated tumours. 

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Case Information

rID: 50661
Case created: 16th Jan 2017
Last edited: 21st May 2017
Inclusion in quiz mode: Included

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