Primitive neuroectodermal tumours of the central nervous system (CNS PNET) is a category of brain tumour that is no longer used, since the World Health Organisation (WHO) updated their guidelines entitled “Classification of Tumours of the Central Nervous System (CNS)” in 2016.

New methods of analysing tumour samples have enabled the identification of slight but important differences between brain tumours previously grouped within the PNET category. For example: genetic differences that can hopefully be targeted by new or repurposed drugs, as we move towards a more personalised approach to brain tumour treatments.

Central nervous system primitive neuroectodermal tumour (CNS PNET) is therefore viewed as a previously useful “umbrella” name for the following tumours, each of which is now featured on a separate page of our website:

• Medulloblastoma
• Pineoblastoma (now classified within Pineal Region Tumours)
• Ependymoblastoma (a name that is also no longer used, with this tumour type being reclassified as an embryonal tumour with multi-layered rosettes or ETMR, within the category of Embryonal Tumours)
• Medulloepithelioma (now classified within Embryonal Tumours)
• Polar spongioblastoma (now classified as a high-grade glioma)

PNET component of glioblastoma multiforme (GBM) brain tumours

A primitive neuronal-like (PNET) component can sometimes be identified in glioblastoma multiforme (GBM) brain tumours. These were previously classified as “glioblastoma with PNET-like component,” but this component is now recognised as characteristic of such tumours, rather than a separate category.