Clinical History
34-year-old female patient presented to the emergency room with headaches and seizures after falling asleep while eating.
Imaging Findings
Head MRI shows a left inferior and middle frontal gyrus enhancing intra-axial mass with strong diffusion restriction and high rCBV (Fig. 1 and 2).
Cervical and thoracic MRI post-contrast images demonstrate multilevel intradural extramedullary enhancing lesions, with associated mass effect and cord oedema. (Fig. 3 and 4)
Discussion
Glioblastoma (GBM) is the most common type of primary malignant brain tumour in adults and the most aggressive high grade glial tumor, rated as Grade IV in the WHO classification. At pathologic examination, GBM shows hypercellularity, nuclear pleomorphism, high mitotic activity, prominent microvascular proliferation and necrosis [1, 2]. They can be grade IV primarily if they arise de novo, or secondary if they progress from a lower grade glioma. Recent WHO tumour classification revision using molecular genetic markers [3] divides GBM into those with isocitrate dehydrogenase mutation ("IDH1 mutant"), and those without this mutation ("IDH1 wild-type"). Patients with IDH1 mutant tumours have a better outcome. The status of MGMT promotor methylation is another prognostic factor that makes these tumours more responsive to temozolomide treatment [2]. MRI is the modality of choice for pre and post-operative evaluation. GBM appears as heterogeneous tumours, with haemorrhage often contributing to heterogeneity. Necrosis is the hallmark of GBM, manifested as an irregular and nodular ring enhancement with gadolinium. GBM is an infiltrating neoplasm, which uses white matter for tumour spread. As a consequence, the FLAIR "oedema" surrounding the tumour also contains tumour infiltration.
DSC perfusion helps to evaluate neoangiogenesis and disruption of the BBB, hallmarks of high-grade gliomas. MR perfusion rCBV is generally elevated in high-grade gliomas, differentiating them from low-grade gliomas. Hypercellular tumors with higher KI-67 show strong diffusion restriction. Lower pretreatment ADC values imply ominous prognosis in supratentorial gliomas. SWI help to evaluate tumour neovascularity and microhaemorrhage, both implying higher tumour grade.
GBM infiltration around the conventional images tumour bed is best detected by MRS, influencing target boundary for radiotherapy and guiding biopsy to the most active tumour regions marked by high Cho/Cr and Cho/NAA ratios. In general, ratios >2 suggest high-grade tumours. Increased lactate and lipid peaks are also markers for high-grade gliomas [2, 3].
GBM white matter spread can infiltrate throughout the brain, expressing distant tumour implantation in pons, cerebellum, medulla and spinal cord. It can also express CSF dissemination by filling sulci and cisterns with carcinomatous meningitis. Focal drop metastases can occur along the spinal cord surface [1, 2]. Patients with GBM treated with wide resection, radiotherapy and temozolomide have shown increased survival, changing the recurrence pattern by increasing the expression of haematogenous metastases and CSF spread. Studies have shown that distant recurrence was higher with methylated MGMT and wild type IDH1 lesions [4].
Differential Diagnosis List
Gliobastoma with leptomeningeal dissemination
Leptomeningeal inflammation: leptomeningitis
Spinal astrocytoma
Ependymoma
Final Diagnosis
Gliobastoma with leptomeningeal dissemination
