Two examples of hemangiopericytoma (HPC): one invading the left petrous ridge and the other within the right insula.
Classic features of HPC: parasagittal location and large tortuous vessels are not demonstrated here.
Mesenchymal (mesodermal) tumor that is dural-based, often parsagittal/falcine.
They have solid and cystic components and characteristically have extensive tortuous (cork-screw) vasculature (prominent flow voids on MRI or tortuous vessels on angiography).
Classic pathologic findings:
Randomly oriented spindle cells in a "patternless pattern" with scant cytoplasm.
Thin-walled vascular spaces called "staghorn" vasculature.
References
Adesina, Adekunle M., Tarik Tihan, Christine E. Fuller, and Tina Young Poussaint. Atlas of Pediatric Brain Tumors. Springer, 2016.
Gray, Frangoise, Charles Duyckaerts, and Umberto De Girolami. Escourolle and Poirier’s Manual of Basic Neuropathology. OUP USA, 2013.
Tonn, Jörg-Christian, Manfred Westphal, and J. T. Rutka. Oncology of CNS Tumors. Springer Science & Business Media, 2010.
Yachnis, Anthony T., and Marie L. Rivera-Zengotita. Neuropathology E-Book: A Volume in the High Yield Pathology Series. Elsevier Health Sciences, 2012.