Pleomorphic xanthoastrocytoma

Martin J Rutkowski MD (Dr. Rutkowski of the University of California, San Francisco, has no relevant financial relationships to disclose.)
Nicholas Butowski MD (Dr. Butowski of the University of California, San Francisco, has no relevant financial relationships to disclose.)
Rimas V Lukas MD, editor. (Dr. Lukas has received honorariums from AstraZeneca as an advisory board member and AbbVie as a guest speaker.)
Originally released February 16, 1999; last updated June 5, 2017; expires June 5, 2020

This article includes discussion of pleomorphic xanthoastrocytoma (PXA), anaplastic PXA, xanthoastrocytoma, and low grade glioma. The foregoing terms may include synonyms, similar disorders, variations in usage, and abbreviations.

Overview

Pleomorphic xanthoastrocytoma (PXA) is a rare subtype of low grade glioma that most frequently presents with seizure and arises most frequently in the temporal lobes. Despite its rarity, this review covers the latest developments in our understanding of pleomorphic xanthoastrocytoma, including its more aggressive anaplastic variant, its ability to transform into high grade glioma, and the new efforts to classify unique molecular alterations.

Key points

 

• Pleomorphic xanthoastrocytoma is a WHO grade 2 neoplasm that is most often diagnosed in children and young adults.

 

• An anaplastic variant exists with poorer overall prognosis; furthermore, classic pleomorphic xanthoastrocytoma has the potential for malignant transformation into a high grade glioma.

 

Epilepsy is the most common presenting sign, likely due to its predilection for the frontal and temporal lobes.

 

• Pathologic features include nuclear and cytoplasmic pleomorphism, xanthomatous changes, and multinucleated cells.

 

• Pleomorphic xanthoastrocytoma has the potential to spread via the cerebrospinal fluid (CSF).

 

• Extent of resection has important implications for prognosis, whereas molecular alterations such as BRAFv600E mutations may hold promise for better understanding their origins and new therapeutic targets.

Historical note and terminology

Pleomorphic xanthoastrocytoma (PXA) is a rare variant of low-grade astrocytoma. The first cases were reported in 1973 as meningocerebral fibrous xanthomas, which were presumed to be of mesenchymal origin (Kepes et al 1973). In 1978, the discovery of the astrocytic marker GFAP allowed Kepes and coworkers to reevaluate these previously reported cases, along with several new ones, and to confirm their astrocytic lineage. Their subsequent report of 12 patients with pleomorphic xanthoastrocytoma was the first to systematically describe its features and to name this new entity—one that reflects its most salient pathologic characteristics (Kepes et al 1979). An evaluation of a pleomorphic xanthoastrocytoma excised in 1930 from a patient who survived for 40 years has yielded what is apparently the earliest known example of this tumor (Geddes and Swash 1999). Nonetheless, the recognition of this tumor is critical for patient care because of its relatively benign prognosis and the consequent implications for management.

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