Anaplastic astrocytoma IDH wild-type

Case contributed by Dr Bruno Di Muzio

Presentation

First seizure episode.

Patient Data

Age: 60 years
CT

CT Brain

Ill-defined hypoattenuating mass involving the left mesial temporal lobe, anterior temporal lobe, basal ganglia, and insula. Local mass effect is seen with gyri effacement, compression over the left lateral ventricle, and mild rightward midline shift. Focal ill-defined wispy enhancement noted within the insular cortex. No calcification or signs of acute haemorrhage. 

MRI

MRI Brain

MRI images confirms the tumour to predominantly involve the cortex, with no haemorrhage, calcifications, and no definitive enhancement seen. 

MRI

MRI Brain (3 months later)

Expansile T2 hyperintense mass involves the left anteromedial temporal lobe, insular, basal ganglia and corona radiata, as well as the left thalamus. Better appreciated on the T2 than the flair sequences, there is also hyperintensity in the medial right temporal lobe which is consistent with contralateral spread of tumour along unexpanded rostrum of corpus callosum. There are 2 separate regions of focal enhancement, in the anterior aspect of the basal ganglia and in the left posterior insula, both with corresponding high-grade features of elevated cerebral blood volume and ADC reduction. 

The degree of expansion related to the tumour has slightly increased and the two nodular enhancing foci are new. 

Case Discussion

Case illustrating an extensive left cerebral hemisphere that has the imaging characteristic of a glioma. The features demonstrated in the last MRI, enhancing foci with restricted diffusion and elevated CBV, favours a high-grade glioma. Spectroscopy was performed at that time (not shown), and was of elevated choline peak and decreased NAA.  

The patient was submitted to a brain biopsy. 

Histology

MICROSCOPIC DESCRIPTION: The sections show features of a moderately cellular glial tumour. Most of the cells appear morphologically astrocytic with elongated, angulated and hyperchromatic nuclei. Occasional tumour cells have round nuclei and perinuclear haloes. Scattered mitoses are seen. No microvascular proliferation or necrosis is present. Sparse calcified deposits are present in the background. The features are consistent with anaplastic astrocytoma. The tumour cells are focally p53 positive. The topoisomerase index is about 10%. IDH1-R132H immunostain is negative. MGMT is also negative (likely methylated). ATRX shows no loss of staining (non-mutated).

  • 1p36: NO DELETION DETECTED
  • 19q13.3: NO DELETION DETECTED 
    • Number of sites scored: 10 
    • Number of cells scored: 200 
    • 1p36/1q25 ratio 0.982 
    • 19q13.3/1p13 ratio: 0.962 
      • REFERENCE CRITERIA: 
        • 1p36/1q25 ratio <0.8 Deletion detected 
        • 19q13.3/19p13 ratio <0.8 Deletion detected 

FINAL DIAGNOSIS: anaplastic astrocytoma (WHO Grade III), IDH wild-type.

Note: Although this tumour is entirely consistent with IDH wild-type molecular subtype, strictly speaking, to conclusively establish this, IDH would need to be sequenced to ensure that a non-IDH1 R132H mutation was present. In practice, an IDH1 R132H negative tumour in an individual over 55-years-of-age makes the possibility of this being IDH mutant remote (<1%), and sequencing is not felt to be necessary by many institutions, and not recommended by the WHO classification of CNS tumours (2016). 

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Case information

rID: 49984
Case created: 13th Dec 2016
Last edited: 22nd Jun 2017
Tag: rmh
Inclusion in quiz mode: Included

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