We describe a rare case of a 33-year-old man presenting with a three-day history of dizziness and memory impairment. On clinical examination, he had a wide-based gait and postural instability. Laboratory tests were unremarkable. The patient underwent a CT scan, which showed an intraventricular heterogeneous mass, with calcifications. An MRI scan was performed, revealing a well-defined intraventricular lesion, with cystic and necrotic areas, hemorrhagic components, areas of restricted diffusion, and a peripheral solid component with post-contrast enhancement. This lesion was ultimately diagnosed as an anaplastic form of pleomorphic xanthoastrocytoma (PXA) (WHO grade 3). Prototypical PXA is a rare low-grade astrocytic tumor, almost always hemispheric. To our knowledge, this is only the third case report to describe an intraventricular PXA. Anaplastic forms of PXA have a more aggressive behavior and should be distinguished from other high-grade astrocytic neoplasms, especially from glioblastoma, isocitrate dehydrogenase (IDH)-wildtype variants (GB). Histopathological features of anaplastic forms of PXA (WHO grade 3) with epithelioid features are very similar to those of epithelioid glioblastoma and its differentiation is a common diagnostic challenge that should prompt genetic testing. Distinguishing between these two entities is crucial since the former is associated with significantly more survival benefits from targeted therapies (MAPK pathway inhibitors).
Keywords: anaplastic; braf; epithelioid glioblastoma; intraventricular tumor; pleomorphic xanthoastrocytoma.
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