Other CNS embryonal tumours

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Other CNS embryonal tumor, was introduced in the WHO 2016 classification of CNS tumors. Some of these tumors of this category has been previously designated as CNS-PNET but this terminology has been abandoned.

Other CNS embryonal tumours
Diagnosis in short

Other CNS embryonal tumorH&E stain.

Synonyms CNS-PNET
LM DDx small round blue cell tumours
IHC S-100 +ve, Syn +/-ve
Site brain, spinal cord

Prevalence rare - typically in children and young adults
Prognosis poor (WHO Grade IV)

General

Other CNS embryonal tumours are a group of primitive neuroeptithelial tumors that are to be classified in distinct molecular groups in the future. Currently it is a exlcusion criteria encompassing four subgroups

  • CNS neuroblastomas
  • CNS ganglioneuroblastomas.
    • often characterized by FOXR2 fusions: CNS neuroblastoma with FOXR2 activation (NB‐FOXR2)
  • CNS medulloepithelioma.
    • but absence of C19MC alteration, otherwise classified as ETMR
  • CNS embryonal tumour, NOS
    • Similarities to astroblastoma: High‐grade neuroepithelial tumours with MN1 alteration (HGNET‐MN1)
    • NUTM1-positive IHC: Ewing's sarcoma family tumour with CIC alteration (EFT‐CIC)
    • BCOR-positive IHC: HGNET BCOR‐altered neuroepithelial tumours

IHC

CNS Ganglioneuroblastoma + Neuroblastoma

  • Syn -/+ve.
  • Vim -ve.
  • GFAP usu -ve.
  • MIB-1 usu high.

Medulloepthelioma

  • Syn +/-ve.
  • NF +/-ve.
  • GFAP usu -ve.
  • CK may be focally +ve.


DDx: