Primitive neuroectodermal tumour

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Primitive neuroectodermal tumour
Diagnosis in short

CNS primitive neuroectodermal tumour H&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 young adults
Prognosis poor (WHO Grade IV)


CNS Primitive neuroectodermal tumour, abbreviated CNS-PNET, is an uncommon neuropathology tumour in the group of embryonal tumours.

It is also known as supratentorial primitive neuroepithelial tumour (supratentorial PNET).

General

  • Should not be confused with peripheral primitive neuroectodermal tumour (abbreviated pPNET[1]), AKA Ewing sarcoma.
  • Currently contains a heterogenous group of poorly differentiated WHO grade IV tumours. Major reoganisation of this group will occur in the upcoming WHO classification.
  • Mainly children and adolescents.
  • Cerebral hemisphere, brain stem or spinal cord.
  • Cerebrospinal dissemination found in up to 1/3 patients.[2]
  • There are currently five ICD-O codes assigned within this group:
    • 9473/3 CNS-PNET, NOS.
    • 9500/3 CNS neuroblastoma.
    • 9490/3 CNS ganglioneuroblastoma.
    • 9501/3 Medulloepithelioma.
    • 9392/3 Ependymoblastoma.
  • Very poor prognosis[3]

Microscopic

Features:

  • Small round blue cell tumour.
    • Focal differentation into astrocytic, neuronal or ependymal phenotypes possible.
  • May have true rosettes (slit-like/oval).
  • Growth in streams or palisades possible ("spongioneuroblastoma").
  • Vascular endothelial proliferations.
  • Fibrillary background in tumours with advanced neuronal maturation (ganglioneuroblastomas).
  • Variable mitotic activity.

Medulloepithelioma

  • Neuroepithelial tumor cells arranged papillary, tubular or trabecular.
  • Pseudostratified with PAS-positive membrane.
  • Medulloepithelioma are grouped with ependymoblastomas and ETANTR into embryonal tumors with multilayered rosettes (ETMR).[4]
  • Not the same tumour as the intraocular medulloepithelioma.[5]

  • Medulloepithelioma/ETMR (H&E)

  • Medulloepithelioma/ETMR (H&E)

  • Medulloepithelioma/ETMR (H&E)

Ependymoblastoma

  • Often supratentorial, well circumscribed.
  • Multilayered ("ependymoblastous") rosettes.
  • High mitotic and proliferative activity
  • Ependymoblastoma are grouped with medulloepithelioma and ETANTR into embryonal tumors with multilayered rosettes (ETMR).[4]

  • Ependymoblastoma. (WC/AFIP)

  • Ependymoblastous rosettes.

  • MIB-1 in ependymoblastous rosettes.

Immunohistochemistry

  • S-100 +ve.
  • INI1 +ve (loss defines tumour as ATRT).
  • LIN28+ve (in ETMR), otherwise -ve. [6]
  • Nestin +ve
  • MAP2 +ve/-ve
  • Vimentin +ve
  • IDH-1 -ve
  • No ATRX loss
  • MIB-1 between 20-80% (usu. 50%)

Molecular genetics

Divergent molecular subgroups are emerging:

  • Loss of 9q / CDKN2A deletions in CNS neuroblastoma[7]
  • Amplification 19q13.42 in ETMR[8]


DDx:

Images

www:

See also

References

  1. ↑ PST. 14 February 2011.
  2. ↑ Horten, BC.; Rubinstein, LJ. (Dec 1976). "Primary cerebral neuroblastoma. A clinicopathological study of 35 cases.". Brain 99 (4): 735-56. PMID 1030655.
  3. ↑ Tulla, M.; Berthold, F.; Graf, N.; Rutkowski, S.; von Schweinitz, D.; Spix, C.; Kaatsch, P. (Sep 2015). "Incidence, Trends, and Survival of Children With Embryonal Tumors.". Pediatrics 136 (3): e623-32. doi:10.1542/peds.2015-0224. PMID 26304823.
  4. ↑ 4.0 4.1 Horwitz, M.; Dufour, C.; Leblond, P.; Bourdeaut, F.; Faure-Conter, C.; Bertozzi, AI.; Delisle, MB.; Palenzuela, G. et al. (Oct 2015). "Embryonal tumors with multilayered rosettes in children: the SFCE experience.". Childs Nerv Syst. doi:10.1007/s00381-015-2920-2. PMID 26438544.
  5. ↑ Korshunov, A.; Jakobiec, FA.; Eberhart, CG.; Hovestadt, V.; Capper, D.; Jones, DT.; Sturm, D.; Stagner, AM. et al. (Jul 2015). "Comparative integrated molecular analysis of intraocular medulloepitheliomas and central nervous system embryonal tumors with multilayered rosettes confirms that they are distinct nosologic entities.". Neuropathology. doi:10.1111/neup.12227. PMID 26183384.
  6. ↑ Korshunov, A.; Ryzhova, M.; Jones, DT.; Northcott, PA.; van Sluis, P.; Volckmann, R.; Koster, J.; Versteeg, R. et al. (Dec 2012). "LIN28A immunoreactivity is a potent diagnostic marker of embryonal tumor with multilayered rosettes (ETMR).". Acta Neuropathol 124 (6): 875-81. doi:10.1007/s00401-012-1068-3. PMID 23161096.
  7. ↑ Pfister, S.; Remke, M.; Toedt, G.; Werft, W.; Benner, A.; Mendrzyk, F.; Wittmann, A.; Devens, F. et al. (Sep 2007). "Supratentorial primitive neuroectodermal tumors of the central nervous system frequently harbor deletions of the CDKN2A locus and other genomic aberrations distinct from medulloblastomas.". Genes Chromosomes Cancer 46 (9): 839-51. doi:10.1002/gcc.20471. PMID 17592618.
  8. ↑ Korshunov, A.; Remke, M.; Gessi, M.; Ryzhova, M.; Hielscher, T.; Witt, H.; Tobias, V.; Buccoliero, AM. et al. (Aug 2010). "Focal genomic amplification at 19q13.42 comprises a powerful diagnostic marker for embryonal tumors with ependymoblastic rosettes.". Acta Neuropathol 120 (2): 253-60. doi:10.1007/s00401-010-0688-8. PMID 20407781.
  9. ↑ Buccoliero AM, Castiglione F, Degl'Innocenti DR, et al. (February 2010). "Embryonal tumor with abundant neuropil and true rosettes: morphological, immunohistochemical, ultrastructural and molecular study of a case showing features of medulloepithelioma and areas of mesenchymal and epithelial differentiation". Neuropathology 30 (1): 84–91. doi:10.1111/j.1440-1789.2009.01040.x. PMID 19563506.
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