Astroblastoma

see Astroblastoma MN1-altered.

Without MN1 rearrangement, you cannot label “astroblastoma” under WHO 2021. Histologically, it's compatible, but diagnostically it should be handled as a high-grade glioma or HGNET NOS pending further molecular clarification.

The term “astroblastoma” is now restricted to cases with confirmed MN1 alteration and should only be used under the entity “Astroblastoma, MN1-altered.”

This implies that:

A diagnosis of astroblastoma requires molecular confirmation of an MN1 gene alteration, typically an MN1::BEND2 fusion, detectable by FISH, RT-PCR, or RNA sequencing.

Without evidence of MN1 alteration, the term “astroblastoma” should not be used, regardless of histological resemblance.

📌 Conclusion: In the absence of MN1 gene alteration, this tumor does not fulfill current WHO criteria for “Astroblastoma, MN1-altered.” Until further molecular studies (such as methylation profiling or RNA sequencing) are available, the most appropriate diagnostic label is:

High-grade neuroepithelial tumor, NOS, with histology consistent with anaplastic astroblastoma.