A polyphenotypic malignant paediatric brain tumour presenting a MN1-PATZ1 fusion, no epigenetic similarities with CNS High-Grade Neuroepithelial Tumour with MN1 Alteration (CNS HGNET-MN1) and related to PATZ1-fused sarcomas.

: Central nervous system high-grade neuroepithelial tumour with MN1 alteration (CNS HGNET-MN1) is a brain tumour methylation class that has recently been identified, based on (epi)genetic profiles of a large CNS-PNETs cohort [1]. This class is characterized by MN1 gene rearrangements, with BEND2 being the most frequently reported fusion partner [1]. Histologically, tumours of this class show pseudopapillary architecture and dense stromal hyalinization [1], features characteristic of astroblastoma. The majority of cases within CNS HGNET-MN1 are represented by the latter, though histopathological aspects resembling ependymomas and not otherwise specified tumours may also be encountered [2]. It remains uncertain, however, if MN1 alterations are an exclusive anomaly of CNS HGNET-MN1.