The patient went to have complete resection of the tumor with the histopathological exam/immunohistochemistry study.

• Microscopy: showing a highly cellular mesenchymal tumoral 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.
• 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 tumor) are consistent with a meningeal hemangiopericytoma grade III (WHO 2016).

Meningeal hemangiopericytomas are rare tumors of the meninges, actually considered to be aggressive versions of solitary fibrous tumors of the dura, They account for less than 1% of all intracranial tumors with up to 10% being diagnosed in children.

The main differential diagnoses are:

• Solitary fibrous tumors of the dura are WHO I grade one lesion, whereas hemangiopericytomas are WHO grade II or III (anaplastic) tumors
• ​Pediatric meningiomas are relatively rare tumors 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