Figure 1: (Top Left) Axial FLAIR demonstrates a left insular infiltrative lesion involving the cortex and white matter. This anaplastic astrocytoma is fairly circumscribed, a less common characteristic in these higher grade lesions. (Top Right) ADC demonstrates no appreciable dark restricted diffusion in this lesion to suggest hypercellularity. (Bottom) Axial T1WI postcontrast shows a small round area of enhancement in the superficial insula, a feature more typical of higher grade glioma. If the T2/FLAIR hyperintensity surrounding this lesion spared the cortex, the enhancing lesion may be more easily mistaken for metastasis with surrounding vasogenic edema.
Figure 2: The medial left frontoparietal complex-appearing anaplastic astrocytoma in this patient demonstrates low T1 signal intensity (top left) and FLAIR hyperintensity (top right) with a mixed-signal hemorrhagic component at its posterolateral aspect. Black signal on the susceptibility-weighted imaging (middle left) also reflect this hemorrhage. The tumor also has a heterogeneous enhancement pattern (middle right, coronal; bottom row, sagittal) that is more typical of higher-grade adult primary brain tumors than of grade II tumors.
- Infiltrating malignant astrocytoma with ill-defined tumor margins and extensive edema
- WHO grade III
- Usually develops from malignant degeneration of low-grade astrocytoma (WHO grade II)
- Commonly dedifferentiates into GBM (~50%) within 2 years
- Focal or diffuse anaplasia, highly proliferative
- Increased cellularity and nuclear atypia; usually no necrosis or microvascular proliferation
All ages affected (fourth and fifth decades of life most common)
- Slight male gender predilection
- Median survival 2–3 years
- Better prognosis with younger age, gross total resection, absence of enhancement, KI-67 index ≤5.1%, and IDH1- or MGMT-positive genetics
- Presenting symptoms dependent on tumor location
- Seizures, headaches, behavioral changes, clinical deterioration in patients with known low-grade astrocytoma
- Treatment: resection, chemotherapy (temozolomide), radiation
- Ill-defined, infiltrating white matter mass
- Location in frontal and temporal lobes most common; brainstem and spinal cord uncommon
- Infiltrates beyond apparent imaging tumor margins
- Expansion and involvement of adjacent cortex common
- Variable enhancement
- Usually nonenhancing, but patchy or nodular enhancement may be present
- Cysts and hemorrhage are uncommon features
- Spreads along white matter tracts, but may spread via cerebrospinal fluid (CSF), leptomeninges, and ependyma
- Hypodense, ill-defined white matter mass
- Hemorrhage and calcification uncommon features
- Usually does not enhance on contrast-enhanced CT, but may show focal or patchy enhancement
- Ring enhancement suggests progression to GBM
- T1WI: isointense to hypointense
- T2WI: heterogeneously hyperintense; presence of flow voids suggests vascular proliferation and progression to GBM
- FLAIR: heterogeneously hyperintense
- DWI: usually no diffusion restriction
- T1WI+C: usually no enhancement; may show patchy or nodular enhancement
- MRS/MR perfusion: decreased NAA, increased Cho/Cr ratio, increased relative cerebral blood volume (rCBV) compared with low-grade astrocytomas, although usually less than glioblastomas
- Diffusion tensor imaging (DTI) may assist in surgical planning
Louis DN, Ohgaki H, Wiestler OD, Cavenee WK, Burger PC, Jouvet A, et al. The 2007 WHO classification of tumours of the central nervous system. Acta Neuropathol 2007;114:547.
Nayak L, et al. Radiotherapy and temozolomide for anaplastic astrocytic gliomas. J Neurooncol 2015;123:129–134.
Ogura R, et al. Immunohistochemical profiles of IDH1, MGMT and P53: Practical significance for prognostication of patients with diffuse gliomas. Neuropathology 2015;35:324–335.
Osborn AG, Salzman KL, Jhaveri, MD. Diagnostic Imaging (3rd ed). Philadelpha, PA: Elsevier, 2016.
Arevalo-Perez J, Peck KK, Young RJ. Dynamic contrast-enhanced perfusion MRI and diffusion-weighted imaging in grading of gliomas. J Neuroimaging 2015;25:792–798.
Gempt J, et al. Multimodal imaging in cerebral gliomas and its neuropathological correlation. Eur J Radiol 2014;83:829–834.
Hirai T, et al. Prognostic value of perfusion MR imaging of high-grade astrocytomas: long-term follow-up study. AJNR Am J Neuroradiol 2008;29:1505–1510.
Tortosa A, et al. Prognostic implication of clinical, radiologic, and pathologic features in patients with anaplastic gliomas. Cancer 2003;97:1063–1071.
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