Gliosarcoma with Primary Skull Base Invasion

Abstract

Gliosarcoma is an uncommon variant of glioblastoma, which commonly demonstrates dural attachment. However, skull base invasion is rarely seen with this entity. Herein, we report a 44-year-old female patient diagnosed with primary intracranial gliosarcoma extensively invading the skull base and muscles of mastication. She presented to our institution with a three-month history of difficult right jaw opening and retro-orbital pressure and one week of severe right-sided postauricular headache. Head CT demonstrated a 6 cm mass with marked bony erosion. Brain MRI at a one-week interval more clearly characterized tumor extension through the right orbit and muscles of mastication, with overall growth to 7 cm and worsening midline shift. The patient underwent a right frontotemporal craniotomy for gross total resection. Pathology confirmed the diagnosis of gliosarcoma, IDH-wildtype (WHO grade IV). Her postoperative course was uneventful and she was discharged at preoperative neurologic baseline. To our knowledge, this is the third reported case of a primary intracranial gliosarcoma with direct invasion of skull base, brain parenchyma, and extracranial compartment. However, this is the first report case of primary GS invading the surrounding musculature and orbit. This case report highlights the rapid aggressiveness of gliosarcomas and further a prior undescribed radiographic and anatomic finding of skull base invasion with this entity.

Figure 1

MRI and CT findings prior to surgery. (a) Sagittal T1-weighted imaging (T1WI) demonstrated a heterogeneous T1 hypointense mass involving a majority of the anterior temporal lobe with associated mass effect and surrounding vasogenic edema. Tumor extends through the greater wing of the sphenoid into the infratemporal fossa. (b) Sagittal postgadolinium T1WI demonstrates avid heterogeneous enhancement. The anterior portion in the soft tissues solidly enhances and intracranially has central necrosis. (c) 3D reconstruction from head CT demonstrates aggressive destruction of the greater wing of the sphenoid. (d) Axial FSE T2-weighted imaging demonstrates the mass to be heterogeneous iso/hypointense tumor with surrounding vasogenic edema suggesting increasing cellularity. (e) Axial postgadolinium T1WI demonstrates avid heterogeneous enhancement with central necrosis intracranially.

Figure 2

Intraoperative photos of the firm, encapsulated tumor penetrating through the temporal bone and involving the temporalis muscle, (a) before and (b) after debulking the tumor extracranially.

Figure 3

Postoperative T1-weighted gadolinium-enhanced MRI of the brain. Both (a) coronal and (b) axial sequences confirm gross total resection of all enhancing tumor. New hyperintensity appreciated at the anterior right temporal pole identifies abdominal fat graft placed during reconstruction.

Figure 4

(a) The hematoxylin and eosin-stained histological sections showed an infiltrating glioma containing microvascular proliferation (arrow) and foci of necrosis surrounded by vaguely pseudopalisading tumor cells (“N”), diagnostic of glioblastoma. (b) Other areas showed a malignant mesenchymal component admixed with the glioblastoma. (c) The GFAP stain highlights the glial component and is negative in the mesenchymal component. (d) In contrast, the reticulin stain demonstrates extensive pericellular deposition of collagen fibers in the mesenchymal component only and is negative in the glial component. These findings support the diagnosis of gliosarcoma (all images at 100x magnification; scale bar = 300 μm).