Neurosurgery notes/Tumours/Gliomas, Glioneuronal Tumors, and Neuronal Tumors/Ependymoma/Supratentorial ependymoma (STE)/Supratentorial ependymoma, YAP1 fusion-positive

Supratentorial ependymoma, YAP1 fusion-positive

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Supratentorial ependymoma (STE)

Definition

  • Essential:
    • Supratentorial tumour with morphological and immunohistochemical features of ependymoma AND
    • Gene fusion involving YAP1
  • Desirable:
    • DNA methylation profile aligned with supratentorial ependymoma. YAP1 fusion positive
    • No immunoreactivity for p65 (RELA) or L1CAM
    • PAS-positive eosinophilic granular bodies

Numbers

  • Uncommon
  • Only described in the paediatric setting thus far
    • Accounting for approximately 7% of all supratentorial ependymomas
  • Account for 6-7.4% of supratentorial ependymomas
  • M:F ratio is 0.3:1

Localisation

  • Within or adjacent to the lateral ventricle

Molecular pathology

  • YAP1-MAMLD1 fusions → recruitment of nuclear factor I (NFI) and TEA domain (TEAD) family members

CNS WHO grading

  • Variable: Need to look at degree of anaplasia

Pathology

Microscopic

  • Composed of relatively uniform cells with small to mediumsized round or angulated nuclei.
  • Ependymal rosettes are present in some tumours.
  • Highly variable Ki67
  • The fibrillary matrix contains PAS-positive eosinophilic granular bodies
  • Common findings:
    • Vascular endothelial proliferation
    • Dystrophic calcification
    • Necrosis.
Supratentorial ependymoma, YAP1 fusion-positive. A, Small, slightly angulated nuclei set against a fibrillary matrix. B, Typical widespread and strong dot-like EMA immunoreactivity.
Supratentorial ependymoma, YAP1 fusion-positive. A, Small, slightly angulated nuclei set against a fibrillary matrix. B, Typical widespread and strong dot-like EMA immunoreactivity.

Macroscopic

  • Similar to other ependymoma
  • Circumscribed and focally haemorrhagic, with a soft consistency.

Origin

  • PAX6-positive radial glial neural stem cells

Clinical features

  • Raised intracranial pressure
  • Focal neurological deficits
  • Seizures

Radiology

  • Tumours are typically isointense to cortex on T2w sequences with well-defined edges and a combination of cystic and multinodular components,
  • Heterogenous enhancement of the solid components and variable perilesional oedema
Supratentorial ependymoma, YAP1 fusion-positive. A, T2-weighted coronal MRI showing a large cystic tumour. B, Ependymoma with YAP1::MAMLD1 fusion. T1-weighted axial MRI showing a large cystic tumour with contrast enhancement of solid tumour parts.
Supratentorial ependymoma, YAP1 fusion-positive. A, T2-weighted coronal MRI showing a large cystic tumour. B, Ependymoma with YAP1::MAMLD1 fusion. T1-weighted axial MRI showing a large cystic tumour with contrast enhancement of solid tumour parts.

Prognosis

  • Despite lesion size, their prognosis appears better compared to other supratentorial ependymomas