Figure 1: (Top Left and Top Right) This pleomorphic xanthoastrocytoma (PXA) demonstrates avid enhancement on postcontrast T1-weighted imaging. The nonenhancing cystic components are also evident. The adjacent enhancing dural thickening (dural tail) is also a variable feature of PXAs. (Bottom) Edema is also variable and can be present, as shown in this axial T2-weighted image.
Figure 2: T1-weighted precontrast (top left) and postcontrast (top right [axial] and bottom left [coronal]) images show a brightly enhancing superficial lesion in the left parietal lobe. Although sometimes present, no dural tail is visible in this example of PXA. A cyst or CSF cleft around the mass is clearly visible on coronal T2-weighted imaging (bottom right). The large amount of surrounding hyperintense edema is also more clearly visible on T2-weighted imaging.
- Supratentorial cortical/peripheral astrocytic tumor
- WHO grade II
- Astrocyte pleomorphism and lipid-containing cells
- Can show anaplastic features (10%–15%)
- Malignant transformation in minority of cases
- Typically afflicts children and young adults (10–36 years of age; mean, 26 years)
- No gender predilection
- Commonly presents with seizures, often of temporal lobe origin
- Overall good prognosis
- 10-year survival, 70%
- Extent of tumor resection and mitotic index are important prognostic factors
- Younger patient age and BRAF mutations are associated with better prognosis
- Hemispheric tumor often located peripherally with cortical ± leptomeningeal involvement
- Temporal lobe > frontoparietal > occipital
- Classically cystic with solid mural nodule; nodule often abuts pial surface
- Can have enhancing dural tail of leptomeningeal attachment
- Often with infiltration of adjacent parenchyma beyond margin of visible tumor
- ±Adjacent cortical dysplasia
- CT Imaging
- Hypodense cystic component; isodense to hyperdense mural nodule or solid components
- Minimal-to-moderate adjacent edema
- Calcification and hemorrhage uncommon
- Strong enhancement of mural nodule/solid components on contrast-enhanced CT imaging
- T1WI: solid component isointense to hypointense to gray matter; cystic component isointense to cerebrospinal fluid (CSF)
- T2WI: solid component isointense to hypointense to gray matter; cystic component isointense to CSF; minimal-to-moderate surrounding T2-hyperintense vasogenic edema
- FLAIR: heterogeneous signal intensity
- DWI: solid components can show diffusion restriction
- T1WI+C: generally strong enhancement; sometimes enhancing dural tail/leptomeninges
- MRI with contrast, including coronal images for temporal lobe evaluation
For more information, please see the corresponding chapter in Radiopaedia.
Contributor: Rachel Seltman, MD
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