Table 1 Proposed morphological variants of PXA
Morphological pattern | Histological description | Differential diagnosis |
|---|---|---|
Classic | Variably pleomorphic cells with eosinophilic cytoplasm, areas of spindling and fascicular growth, and at least focal lipidized neoplastic cells with EGBs | Ganglioglioma, Pilocytic astrocytoma, Giant cell GBM |
Ganglioglioma-like | Compact and fasciculated tumor with ganglion cell differentiation and EGBs | Ganglioglioma and other low-grade glial neoplasms with ganglion cell differentiation |
Glioblastoma-like | Features resembling conventional glioblastoma, including mitotically active tumor with pseudopalisading necrosis and microvascular proliferation | Conventional GBM IDH-wt and HGG IDH/H3-wt |
Epithelioid glioblastoma-like | Predominantly epithelioid cells with distinct cell borders and round nuclei with prominent nucleoli arranged in a solid pattern | GBM IDH-wt and HGG IDH/H3-wt with epithelioid features: non-flat copy-number profile, including gene amplifications (CDK4, CDK6, EGFR, MDM2, MDM4, MET) |
Astroblastoma-like | Astroblastic rosettes might be found at least focally in tumors with areas of classic PXA and absence of MN1 fusions | Astroblastoma (ABM): presence of MN1 alterations |
Spindle cell | Spindle cell pattern in the majority or entirety of the specimen | Meningothelial and mesenchymal, non-meningothelial neoplasms |
Embryonal-like | Monomorphic undifferentiated and/or rhabdoid cells reminiscent of true embryonal neoplasms, including INI-1 (SMARCB1) loss | Atypical teratoid/rhabdoid tumor and other Embryonal tumors |