Background: Pleomorphic xanthoastrocytoma (PXA), anaplastic pleomorphic xanthoastrocytoma (A-PXA), and epithelioid glioblastoma (E-GBM) show overlapping features. However, little is known about their clinical characteristics, molecular features and relationship with progression.
Methods: Fourteen patients diagnosed at Nanfang Hospital from 2016 to 2019 were enrolled, including eleven PXA patients, two A-PXA patients, and one E-GBM patient. All tumour tissue samples of the fourteen patients were examined by immunohistochemical staining (MGMT, VEGF, BRAF-V600E, etc.). The recurrent tumour tissue of the patient with E-GBM arising from A-PXA was screened to detect 11 glioma markers (MGMT, BRAF-V600E, etc.) and chromosome 1p/19q by next-generation sequencing (NGS).
Results: The mean age of 13 patients with PXA or A-PXA was 25.4 years; twelve of these patients had tumours at supratentorial regions. VEGF positivity was detected in the tumour samples of 13 patients, MGMT positivity in 10 patients, and BRAF-V600E positivity in 7 patients. For the tumour sample of the E-GBM patient who survived for up to 10 years after the fourth resection, BRAF V600E was wild type in the sample obtained from the first surgery, while it was mutant in the second, third, and fourth surgeries. In contrast, the promoter status of MGMT in the four surgeries was unmethylated. The NGS results showed that the mutation frequencies of BRAF V600E in the second, third and fourth surgeries were 14.06%, 9.13% and 48.29%, respectively.
Conclusions: Collectively, the results suggest that patients with A-PXA may relapse multiple times and eventually progress to E-GBM with the BRAF-V600E mutation.