Presentation
Not available.
Patient Data
No report data found 07/2009
14 x 14 x 17 mm (AP x ML x SI) extraaxial mass centered on the inferior aspect of the falx between the frontal lobes shows T1/T2 isointensity and diffuse contrast enhancement, spare a punctate focus inferiorly which may reflect calcification or flow void. Findings are consistent with a meningioma.
Small dural tail extending superiorly along the falx. The mass is slightly asymmetrical to the right but involves both sides of the falx. No adjacent cerebral edema. The posterior aspect of the adjacent inferior sagittal sinus enhances normally with no evidence of direct invasion or thrombosis.
No other intra or extraaxial mass lesion nor abnormal areas of enhancement.
Evidence of previous right frontal craniotomy and small area of susceptibility in the right parietal subcutaneous tissues.
No hydrocephalus.
Note is also made of a 4cm fat containing subcutaneous mass in the right occipital region, incompletely imaged and containing a few thin internal septations - this presumably reflects a low grade fat containing tumor, however without pre and post contrast imaging of the entire lesion, a higher grade component cannot be excluded.
Conclusion:
17 mm frontal inferior falcine meningioma.
There has been an interval increase in size of the previously described falcine meningioma when compared to the previous MRI.
Enhancing parasagittal meningioma measures 2.1 x 2.1 x 2.2 cm.
Lipoma in the subcutaneous soft tissues overlying the right occipital bone is again demonstrated.
No other abnormality is demonstrated within the limitations of the single sequence provided.
Paraffin sections show a densely hypercellular dural based tumor. Tumor cells have moderately pleomorphic overlapping hyperchromatic nuclei and a small amount of cytoplasm. These are arranged in diffuse sheets within a vascular stroma. Vessels are predominantly capillary in type. Some "staghorn" vessels are noted. Scattered mitotic figures are identified (2/20 HPF). No areas of necrosis are seen. Tumor is seen to push against but not invade underlying brain parenchyma. Immunohistochemistry shows patchy CD34 staining in the tumor cells. They are also bcl-2 and CD99 positive. The topoisomerase index is 3-4%. EMA and inhibin are negative. The features are of meningeal hemangiopericytoma (WHO grade II).
FINAL DIANOSIS: solitary fibrous tumor of the dura (previously hemangiopericytoma) - 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.
Case Discussion
Solitary fibrous tumors of the dura are rare tumors of the meninges, often presenting as a large and locally aggressive dural mass, frequently extending through the skull vault. They are difficult to distinguish from the far more common meningioma, but are treated similarly with surgical resection with or without radiotherapy to reduce the risk of recurrence, which is high.