Dysembryoplastic neuroepithelial tumour (DNET)

Case contributed by A.Prof Frank Gaillard

Presentation

Seizures

Patient Data

Age: 58
Gender: Female

There is a 10mm x 6mm x 8mm cyst-like mass lesion within the left amygdala. The lesion within the left amygdala does not demonstrate contrast enhancement, increased perfusion or restricted diffusion, but does have partial T2 suppression on flair with a residual bright rim of signal. Spectroscopy demonstrates mildly decreased NAA, increased Cho and raised Myo-Ins within the lesion. The mass lesion impresses upon and flattens the left hippocampal head, however, the internal architecture and signal of the left hippocampal body and tail is preserved. There is loss of grey-white matter differentiation along the left para-hippocampal gyrus - this may be seizure-related or as a result of associated cortical dysplasia.

The right hippocampus has normal signal and internal architecture.No remote intra- or extra-axial mass lesions, acute haemorrhages or collections.

No regions of abnormal supra- or infra-tentorial suscepability blooming. No regions of abnormal parenchymal or meningeal enhancement.

Conclusion:

There is a mass lesion within the left amygdala with impression on the left hippocampal head.

The body and tail of the left hippocampus has normal signal and internal architecture, however, there is loss of grey-white matter definition within the adjacent left para-hippocampal gyrus that may be secondary to associated cortical dysplasia.

The left amygdala lesion most likely represents a DNET or a low grade glial series tumour - the spectroscopy trace favours low grade glial series tumour.

Case Discussion

The patient went on to have a resection. 

Histology

MICROSCOPIC DESCRIPTION:

1. The sections of temporal neocortex and white matter show a disturbance of cortical lamination with a haphazard arrangement of enlarged dysmorphic neurones and segments in which there is persistence of a columnar arrangement of cortical neurones. No balloon cells are seen. There is no evidence of tumour. The features are of cortical dysplasia ILAE - Type IIIb.

2. The sections show mildly hypercellular parenchyma in which there is admixture of haphazardly arranged ganglion cells, reactive astrocytes and cells with small round hyperchromatic nuclei. These last cells have a vague columnar arrangement. Many ganglion cells are noted within spaces filled with loose myxoid/mucinous material. No mitotic figures are identified and there is no microvascular proliferation and no necrosis. The features are of dysembryoplastic neuroepithelial tumour (DNET). The topoisomerase labelling index is <1%.

DIAGNOSIS:

  1. Cortical dysplasia - ILAE Type IIIb;
  2. Dysembryoplastic neuroepithelial tumour (DNET).
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Case information

rID: 32956
Case created: 23rd Dec 2014
Last edited: 30th Oct 2017
Inclusion in quiz mode: Included

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