Background: Gliosarcoma refers to an uncommon astrocytic tumor of the central nervous system. These tumors include both glial and mesenchymal components by definition, and are extremely malignant. Gliosarcomas are particular to tumors with distinct gliomatous and sarcomatous constituents, and are distinguished from gliobastomas which have undergone mesenchymal metaplasia. Gliosarcomas encompass 2-8% of all glioblastoma cases and tend to occupy the supratentorial regions of the brain, especially the temporal lobe. Rare infratentorial lesions including the cerebellar hemisphere, intraventricular, and multi-focal tumors have also been reported. Accurate neuroimaging diagnosis is critical and diffusion tensor imaging (DTI) and spectroscopy can be useful to differentiate from inflammatory disease.
Methods: We report a 38 year-old Caucasian male with a right parietal lobe glioblastoma. The patient presented with new onset tonic-clonic seizures lasting approximately five minutes associated with postictal confusion and incontinence. The patient had conventional brain MRI scans including DTI. MRI data was processed to obtain tractography and fractional anisotropy (FA) maps. MR images were examined for location and extent of tumor as well as invasion, destruction or displacement of brain parenchyma and white matter tracts.
Results: Noncontract CT revealed no abnormality and emergent MR imaging shows a ring-enhancing lesion measuring 3.1x2.2x3.1 cm at the junction of the right parieto-occipital region. The lesion abuts the dural surface, characteristic of gliosarcoma. Extensive surrounding edema causing complete effacement of the posterior horn of the right lateral ventricle, parietal effacement of the anterior floor of the right ventricle, and a 1.2 cm right to left midline shift were observed. Mild diffuse enhancement in the region of the splenium of the corpus callosum was likely compatible with seizure activity. Increased signal intensity of axial FLAIR image was seen in this area after four weeks. Fractional anisotropy is reduced at the tumor site suggesting an aggressive and invasive lesion. Diffusion tensor tractography shows destruction of white matter tracts compatible with destruction rather than invasion of parenchyma. Histopathology confirms gliobastoma multiforme, demonstrating mixed glial and sarcomatous components. However, GFAP was strongly positive in both areas and a reticulin stain was not increased in the sarcomatorus areas excluding the sarcomatous variant of glioblastoma.
Conclusion: We report the imaging findings of a rare gliosblastoma radiographically presenting as a gliosarcoma due to its location along the dural surface, but with lack of pathologic findings. Gross total tumor resection was performed and the patient and is undergoing adjuvant radiation therapy with concurrent chemotherapy.
Mehta, Akshita; Levy, Lucien M.; Almira-Suarez, M. Isabel; and Tu, Raymond, "Neuroimaging of Unusual Glioblastoma Using Diffusion Tensor Imaging" (2014). GW Research Days 2014. Paper 2.