Gliosarcoma

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Gliosarcoma
Axial MRI of Gliosarcoma
Tumor Class	Astrocytoma
Cell of origin	Glial
WHO Grade	IV
Survival	6 Months
Treatment	Surgery, Radiation, Chemotherapy
Histologic Features
Radiographic Features

Definition

Gliosarcoma is a histological variant of Glioblastoma multiforme (GBM) characterized by a biphasic tissue pattern with alternating areas of glial and mesenchymal differentiation. Gliosarcoma corresponds to WHO Grade IV astrocytoma.

Epidemiology

Gliosarcoma accounts for about 2% of all GBMs. The mean age of occurrence is 53 years. There is a male predominance (1.8:1).

Localization

Gliosarcomas are most often supratentorial, occurring in descending frequency in the temporal, frontal, parietal and occipital lobes.

Clinical presentation

Most patients present with new-onset seizure or paresis.

Imaging

Angiographic examination demonstrates a mixed dural and pial vascular supply. On MRI, these lesions may be mistaken for a meningioma or hemangiopericytoma.

Photomicrograph of gliosarcoma showing biphasic pattern of glial and sarcomatous components.

Macroscopy

Gliosarcomas are biphasic lesions composed of a firm, sarcomatous component, often located superficially, and a more typical gliomatous component.

Histopathology

A biphasic tissue pattern displaying gliomatous and mesenchymal (e.g. neoplastic spindle cells imbedded in a reticulin-positive stroma) components is necessary for diagnosis.

Molecular genetics

Gliosarcomas possess a complement of molecular mutations similar to those seen in GBMs (see Molecular genetics of Gliomagenesis), but generally lack evidence of EGFR amplification of overexpression.

Prognosis

Large trials have failed to demonstrate a difference in outcomes for gliosarcoma and GBM.