Presentation
Epilepsy
Patient Data
The MRI sequences demonstrate a large well-defined extra-axial left frontal mass of parasagittal location centred on the olfactory groove/planum sphenoidale with CSF cleft sign. It displays a low signal on T1WI, inhomogeneous high signal on T2WI with central areas of bleeding causing high signal on T1WI, and low signal on T2WI/GE as well as focal cystic changes. The postcontrast sequences show an intense and heterogeneous enhancement with central necrosis. A mass effect is noted on the falx cerebri and frontal horns.
Case Discussion
The patient went to have complete resection of the tumour with the histopathological exam/immunohistochemistry study.
- Microscopy: showing a highly cellular mesenchymal tumoural proliferation with areas of infiltration of the peripheral glial tissue as well as areas of necrosis with a stromal vascular pattern giving a "staghorn" appearance.
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Immunohistochemestry:
- CD34: positive
- STAT6: positive
- GFAP: negative
- EMA: negative
- Ki-67: proliferation index around 30%
- Conclusion: The immunohistochemistry profile correlated to the microscopic appearances as well as the MRI features (meningeal tumour) are consistent with a meningeal haemangiopericytoma grade III (WHO 2016).
Meningeal haemangiopericytomas are rare tumours of the meninges, actually considered to be aggressive versions of solitary fibrous tumours of the dura, They account for less than 1% of all intracranial tumours with up to 10% being diagnosed in children.
The main differential diagnoses are:
- Solitary fibrous tumours of the dura are WHO I grade one lesion, whereas haemangiopericytomas are WHO grade II or III (anaplastic) tumours
- Paediatric meningiomas are relatively rare tumours with an incidence ranging from 0.4 to 4.6% before the age of 16 years 1. Usually seen in the setting of a neurofibromatosis type 2 (NF2) 1.
Additional contributor: R. Bouguelaa, MD