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
Crespo-Rodríguez AM, Smirniotopoulos JG, Rushing EJ. MR and CT imaging of 24 pleomorphic xanthoastrocytomas (PXA) and a review of the literature. Neuroradiology 2007;49:307–315. doi.org/10.1007/s00234-006-0191-z.
Ida CM, Rodriguez FJ, Burger PC, et al. Pleomorphic xanthoastrocytoma: natural history and long-term follow-up. Brain Pathol 2015;25:575–586. doi.org/10.1111/bpa.12217.
Louis DN, Ohgaki H, Wiestler OD, et al. The 2007 WHO classification of tumours of the central nervous system. Acta Neuropathol 2007;114:547. doi.org/10.1007/s00401-007-0243-4.
Moore W, et al. Pleomorphic xanthoastrocytoma of childhood: MR imaging and diffusion MR imaging features. AJNR Am J Neuroradiol 2014;35:2192–2196. doi.org/10.3174/ajnr.A4011.
Osborn AG, Salzman KL, Jhaveri MD. Diagnostic Imaging (3rd ed). Elsevier, Philadelphia, PA; 2016.
Yu S, He L, Zhuang X, et al. Pleomorphic xanthoastrocytoma: MR imaging findings in 19 patients. Acta Radiol 2011;52:223–228. doi.org/10.1258/ar.2010.100221.
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