Pleomorphic xanthoastrocytoma

Pleomorphic xanthoastrocytoma (PXA) is a rare, low-grade brain tumor (WHO grade II) that arises from astrocytes, the supportive cells of the central nervous system. It most commonly occurs in the cerebral hemispheres, particularly the temporal lobe, and tends to involve the superficial cortex and overlying meninges. PXA predominantly affects children and young adults. The tumor is characterized histologically by pleomorphic (variably shaped) cells, lipid-laden (xanthomatous) tumor cells, and a dense reticulin network. A subset of PXAs may undergo anaplastic transformation to WHO grade III (anaplastic pleomorphic xanthoastrocytoma), which carries a more aggressive clinical course. The most common presenting symptom is seizures, often with a long history prior to diagnosis. Other symptoms may include headaches, focal neurological deficits, and increased intracranial pressure depending on tumor size and location. Many patients have a relatively favorable prognosis compared to other astrocytic tumors. A frequent molecular finding is the BRAF V600E mutation, which is present in approximately 60-80% of cases and has become an important therapeutic target. The primary treatment for pleomorphic xanthoastrocytoma is surgical resection, with gross total resection offering the best long-term outcomes and high rates of progression-free survival. When complete resection is not achievable or when the tumor recurs, adjuvant radiation therapy may be considered. For tumors harboring the BRAF V600E mutation, targeted therapies such as BRAF inhibitors (e.g., vemurafenib, dabrafenib) alone or in combination with MEK inhibitors (e.g., trametinib) have shown promising results, particularly in recurrent or progressive disease. Conventional chemotherapy may also be used in select cases, though its role is less well established.

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