Presentation
Headache
Patient Data
A large lobulated mass is seen centered on the falx, with prominent positive mass effect and surrounding vasogenic edema. The mass is heterogeneous in density with much of it being somewhat hyperdense.
A large mass arising from the falx is noted, with 'destruction' of the falx. The mass is multilobulated, and has numerous peripheral flow voids. Areas of hemorrhage and cystic change are noted. ADC demonstrates low values, consistent with hypercellular nature of the lesion.
Conclusion
The differential is between a meningioma and a hemangiopericytoma. Presence large peripheral flow voids and multi lobulation and 'destruction' of the falx, favors the latter.
Case Discussion
The patient went on to have surgery.
Histology
MICROSCOPIC DESCRIPTION: Sections show a hypercellular spindle cell tumor with prominent haemangiopericytomatous "staghorn" blood vessels. Tumor cells are arranged in solid sheets containing abundant pale eosinophilic cytoplasm, elongate oval moderately pleomorphic nuclei with coarse chromatin and inconspicuous nucleoli. Focally the tumor demonstrates myxoid degeneration (specimen 5). No sarcomatous elements, necrosis or atypia is seen. There are up to 9 mitoses per 10 hpf identified.
Immunohistochemical results show tumor cells stain: CD34+ (focal), BCL2+, CD99+, STAT6+ (focal), EMA- and PgR-. The Topoisomerase proliferation index is approximately 5-10%.
FINAL DIAGNOSIS:
Solitary fibrous tumor of the dura (previously hemangiopericytoma) - WHO grade III.
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.
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