Central Nervous System Solitary Fibrous Tumor/Hemangiopericytoma Penetrating the Skull Bone: An Unusual Presentation.

Background: Central nervous system (CNS) solitary fibrous tumor/hemangiopericytoma (SFT/HPC) is a soft tissue neoplasm that accounts for <1% of all intracranial tumors. Its growth will be mostly intracranial, usually along the sinuses. We have reported a rare case of direct extracranial extension of CNS SFT/HPC penetrating the frontal bone.

Case Description: A 64-year-old woman had visited our institution for treatment of a forehead mass. With the impression that it was a subcutaneous mass, we had planned a simple excision with the patient under local anesthesia. However, the intraoperative findings showed extension of the mass into the skull and attachment to the dura mater. Brain magnetic resonance imaging showed a 1.8-cm solid mass with an adjacent skull defect, and examination of the biopsy specimen confirmed the diagnosis as grade II CNS SFT/HPC. Definitive excision was performed by en bloc tumor resection with a 2-cm safety margin. Adjuvant radiotherapy was performed with 60 Gy in 30 fractions. The patient showed no signs of recurrence or metastasis during 2 years of follow-up.

Conclusions: The present case has shown that CNS SFT/HPC can infiltrate the full thickness of the skull bone and grow extracranially, even if low grade. However, the unusual presentation of the present made early exploration and total resection possible.