Unfortunately, I don't know the age of this patient, which would help guide the differential diagnosis . This mass appears to be arising from the posterior fourth ventricle. Intraventricular GBMs are uncommon but not rare. GBM may have occasional calcification and may be markedly hypervascular with flow voids, simulating AVM on angio. The tumor may become more necrotic and calcified with treatment.
Prognosis is dismal, with a median survival measured in months.