Gliosarcoma is a biphasic tumor of the central nervous system,
associating a glioblastoma-type glial contingent and a sarcomatous contingent.This tumor was first described by Stroebe in 1895 [1].
Cerebral gliosarcomas are rare tumors,
accounting for 0.8 to 8% of all glioblastomas [2].
The average age of onset of gliosarcomas ranges from 40 to 60 years,
with an average age of about 50 years.
It affects both sexes with a slight male predominance [2].
The involvement of the pediatric population is extremely rare; only a dozen cases are reported in the literature [3].
In our study,
both patients were male with an average age of 48 years,
which is consistent with data from the literature.
Localization is essentially supratentorial,
affecting the temporal region in more than 65% of cases; the frontal,
parietal and occipital regions can be reached in order of decreasing frequency [1].
Very rare cases of gliosarcoma of the posterior fossa have been described [4].
Similarly intraventricular localization remains extremely rare [5].
The clinical symptomatology is polymorphic depending on the affected area.
Nevertheless,
it remains dominated by HTIC syndrome,
motor deficit and seizures [6].
In both patients,
the clinical symptomatology was made by the association of a HTIC syndrome with a contralateral motor deficit.
In addition,
one of our two patients also had the notion of associated seizures.
The diagnosis is evoked on imaging (CT and MRI in particular) and confirmed by the histological and immunohistochemical study.
Imaging represents an essential step in the diagnostic approach of gliosarcomas,
and especially in the evaluation of therapeutic possibilities and the follow-up of these tumors [7].
The most accessible examination currently is the brain scan.
It is often performed as first-line for HTIC syndrome,
and magnetic resonance imaging (MRI) supplementation is often required for complete characterization of the lesion [7].
Diffusion imaging,
perfusion and spectroscopic imaging techniques available on modern imagers are readily achievable in clinical practice.
They provide different and complementary information to that provided by morphological imaging [7].
In CT,
the usual aspect is that of a superficial mass,
well circumscribed,
spontaneously hyperdense,
and exerting a mass effect on the median structures.
In some studies,
gliosarcoma has been described as an essentially isodense or hypodense lesion [7].
After injection of the contrast,
there is peripheral enhancement in a heterogeneous or irregular crown [7].
In MRI,
the cerebral gliosarcoma achieves a characteristic appearance showing a well-circumscribed tumor,
intra-axial,
coming into contact with the dura mater,
with areas of cystic changes and vasogenic edema around [8].
In T2 weighting,
the intensity of the signal is intermediate,
similar to that of the gray matter,
but hypointense in comparison with other glial tumors [8].
In T1 weighting,
some tumors show significant enhancement after gadolinium injection.
This enhancement is diffuse and heterogeneous with a more intense signal at the periphery.
Other tumors can make a so-called ring-like image surrounding a hypointense center.
These zones of enhancement are isointenses in T2 [8].
The diagnosis of gliosarcoma must therefore be evoked in front of any hypointense tumor in T2,
with a primitive intra- axial seat and coming into contact with the dura mater [9].
Thallium 201 scintigraphy can be used to detect different brain tumors including glioblastomas [10].
Gliosarcoma captures thallium 201 [10].
Most gliosarcomas develop de novo.
In some cases,
they may occur after radiotherapy treatment of a pre-existing glioblastoma and are therefore called secondary gliosarcomas [11].
The treatment is essentially based on surgery and radiotherapy.
On the other hand,
the place of chemotherapy remains controversial.
The prognosis remains pejorative with a very high recidivism rate and a median survival of 11 months.