Solitary fibrous tumor (hemangiopericytoma)

Case contributed by Frank Gaillard



Patient Data

Age: 70 years

A large hyperdense lobulated vividly enhancing extra-axial mass is seen adjacent to the falx. 

Large right extra-axial posterior parafalcine mass is heterogeneous, but of similar signal intensity to brain parenchyma on T1 and T2-weighted imaging. Slightly increased signal on FLAIR. Diffuse homogeneous bright enhancement with central nonenhancing T2 hyperintense component. There is markedly lobulated surface contour.

The mass compresses the trigone of the right lateral ventricle, displaces and compresses the splenium of the corpus callosum, and compresses the medial right occipital lobe. There is abnormal T2 hyperintensity in the white matter of the right parietal, posterior right frontal, and right occipital lobes. There are large vessels along the surface of the mass.

Markedly elevated relative cerebral blood volume. MR spectroscopy demonstrates marked elevation of choline, depletion of creatine and NAA. No alanine peak (if present, would favor meningioma).

Conclusion: Large right parafalcine extra-axial mass likely to represent a hemangiopericytoma with the obvious differential of a meningioma.

Case Discussion

The patient went on to have surgery.


Paraffin sections show a densely cellular, dural-based tumor. Tumor cells have pleomorphic round, oval and elongated nuclei with vesicular chromatin and a variable amount of cytoplasm and are arranged in solid sheets in a fibrous stroma. The formation of thin-walled "staghorn" vascular channels is noted in many areas. Five mitotic figures are identified in 20 high power fields. There are several foci of geographic necrosis. One of these is surrounded by a palisaded arrangement of tumor cells. No evidence of brain invasion is seen.

Immunohistochemistry results show tumor cells stain: STAT6+ (focal), Co99+, BCL2+, EMA-, PR-, SST R2- and Co34-. The Topoisomerase proliferation index is approximately 15%.

FINAL DIAGNOSIS: solitary fibrous tumor of the dura (previously hemangiopericytoma/solitary fibrous tumor) - WHO Grade II.

Note: Due to molecular/genetic similarities hemangiopericytomas are no longer recognized as distinct entities. Instead, they represent cellular higher-grade solitary fibrous tumors. In the 2016 revised 4th Edition of the WHO classification of CNS tumors, they were grouped together under one diagnosis (solitary fibrous tumor/hemangiopericytoma), and in the 2021 5th edition the term hemangiopericytoma was dropped entirely. 

How to use cases

You can use Radiopaedia cases in a variety of ways to help you learn and teach.

Creating your own cases is easy.