Pleomorphic xanthoastrocytoma (PXA)
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PXA is a low-grade astrocytic neoplasm of young life and early adulthood, with superficial localization ion the cerebral hemispheres and involvement of the mininges. PXA is a WHO Grade II astrocytoma.
PXA typically develops in children and young adults. It accounts for less than 1% of all astrocytic neoplasms.
PXA typically occurs in the superficial cerebral hemispheres, most commonly in the temporal lobe. Involvement of the meninges is frequent. There are some reports of PXA in the cerebellum.
Most patients present with a long history of seizures.
On MRI, PXA are discrete, cystic lesions associated with a mural nodule.
PXA are discrete lesions, often cystic in nature, with an associated mural nodule. These lesions are often attached to the meninges.
PXA is a pleomorphic tumor composed of fibrillary and giant, often multi-nucleated, neoplastic astrocytes. Diagnostic hallmarks include large, xanthomatous cells expressing GFAP, a dense intercellular reticulin network, and lymphocytic infilitrates. Eosinophilic granular bodies are frequently encountered. Necrosis is a poor prognostic indicator and degeneration to GBM is associated with this feature.
The molecular genetics of PXA have not been elucidated, though gains of chromosomes 3, 7 and 1q are not uncommon.
Recurrence-free survival has been reported as 72% at 5 years and 61% at 10 years. Overall survival has been estimated as 81% at 5 years and 70% at 10 years. Extent of resection at initial presentation appears to be the most important factor for both recurrence-free and overall survival.