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Pleomorphic Xanthoastrocytoma (PXA)

Last Updated: March 27, 2020

Open Table of Contents: Pleomorphic Xanthoastrocytoma (PXA)

Figure 1: This PXA demonstrates avid enhancement on postcontrast T1WI (top row). The nonenhancing cystic components are also evident. The adjacent enhancing dural thickening (dural tail) is also a variable feature of PXA. Edema is also variable and may be present, as on this axial T2WI (bottom).

Figure 2: T1 pre- (top row left) and post-contrast (top row right – axial, bottom row 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 image (bottom row right). The large amount of surrounding hyperintense edema is also more clearly visible on T2.

Basic Description

  • Supratentorial cortical/peripheral astrocytic tumor

Pathology

  • WHO II
  • Astrocyte pleomorphism and lipid-containing cells
  • May show anaplastic features (10-15%)
  • Malignant transformation in minority of cases

Clinical Features

  • Typically afflicts children and young adults (10-36 years; 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 important prognostic factors
    • Younger patient age and BRAF mutations associated with better prognosis

Imaging Features

  • General
    • Hemispheric tumor often located peripherally with cortical ± leptomeningeal involvement
    • Temporal lobe > frontoparietal > occipital
    • Classically cystic with solid mural nodule; nodule often abuts pial surface
    • May have enhancing dural tail of leptomeningeal attachment
    • Often with infiltration of adjacent parenchyma beyond margin of visible tumor
    • ± adjacent cortical dysplasia
  • CT

    • Hypodense cystic component; iso- 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
  • MRI

    • T1WI: solid component iso- to hypointense to gray matter; cystic component isointense to CSF
    • T2WI: solid component iso- 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 may show diffusion restriction
    • T1WI+C: generally strong enhancement; sometimes enhancing dural tail/leptomeninges

Imaging Recommendations

  • MR with contrast including coronal images for temporal lobe evaluation

For more information, please see the corresponding chapter in Radiopaedia.

Contributor: Rachel Seltman, MD

DOI: https://doi.org/10.18791/nsatlas.v1.03.01.35

References

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.

Ida CM, Rodriguez FJ, Burger PC, et al. Pleomorphic xanthoastrocytoma: natural history and long-term follow-up. Brain Pathol. 2015;25:575-586

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.

Moore W, et al. Pleomorphic xanthoastrocytoma of childhood: MR imaging and diffusion MR

Osborn AG, Salzman KL, Jhaveri MD. Diagnostic Imaging (3rd ed). Philadelphia, PA: Elsevier, 2016.

Yu S, He L, Zhuang X, et al. Pleomorphic xanthoastrocytoma: MR imaging findings in 19 patients. Acta Radiol. 2011;52: 223-228.

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