Pleomorphic Xanthoastrocytoma; Clinicopathological spectrum of An Intriguing neoplasm

A "masked" pleomorphic xanthoastrocytoma

The latest WHO Classification of tumours of the Central Nervous System (CNS) emphasizes the necessity of an integrated diagnostic approach during the workup of a CNS neoplasm. In addition to the mutational status, assessment of methylation profile of a tumour emerged as a helpful (often necessary) tool to make a correct and unequivocal diagnosis. Here we present a case of a Pleomorphic Xanthoastrocytoma with clinical, radiological and histopathological findings remarkably overlapping with a recently described paediatric-type glioma namly Polymorphic Low-grade Neuroepithelial Tumour of the Young (PLNTY). The differential diagnosis here discussed represents a methodological paradigm in the modern neuropathology. In fact, the presentation of this case is a demonstration that in day-to-day practice, clinical, radiological, and histopathological data can all be misleading, and the correct diagnosis can only be reached by integration with molecular analysis. In the modern neuro-oncology, it is by far mandatory for all the specialists dealing with cerebral tumours to "contaminate" their own cultural heritage with other ones, to optimally manage a patient with CNS tumour.

Exploring DNA Methylation for Prognosis and Analyzing the Tumor Microenvironment in Pleomorphic Xanthoastrocytoma

Pleomorphic xanthoastrocytoma (PXA) is a rare type of brain tumor that affects children and young adults. Molecular prognostic markers of PXAs remain poorly established. Similar to gangliogliomas, PXAs show prominent immune cell infiltrate, but its composition also remains unknown. In this study, we correlated DNA methylation and BRAF status with clinical outcome and explored the tumor microenvironment. We performed DNA methylation in 21 tumor samples from 18 subjects with a histological diagnosis of PXA. MethylCIBERSORT was used to deconvolute the PXA microenvironment by analyzing the associated immune cell-types. Median age at diagnosis was 16 years (range 7-32). At median follow-up of 30 months, 3-year and 5-year overall survival was 73% and 71%, respectively. Overall survival ranged from 1 to 139 months. Eleven out of 18 subjects (61%) showed disease progression. Progression-free survival ranged from 1 to 89 months. Trisomy 7 and CDKN2A/B (p16) homozygous deletion did not show any association with overall survival (p = 0.67 and p = 0.74, respectively). Decreased overall survival was observed for subjects with tumors lacking the BRAF V600E mutation (p = 0.02). PXAs had significantly increased CD8 T-cell epigenetic signatures compared with previously profiled gangliogliomas (p = 0.0019). The characterization of immune cell-types in PXAs may have implications for future development of immunotherapy.

Intradural extramedullary pleomorphic xanthoastrocytoma: A case report

Background:

Pleomorphic xanthoastrocytomas (PXAs) are uncommon intradural and typically intramedullary astrocytic central nervous system tumors. Although they commonly occur supratentorially, they are rarely seen in the spine.

Case Description:

A 43-year-old male presented with cervical neck pain and right-sided radicular symptoms. He was found to have an intradural extramedullary mass at the C5–C6 level. The lesion was fully excised and proved to be a PXA. Of interest, the lesion did not recur on postoperative MR imaging studies obtained 7 months later.

Conclusion:

While rare, primary intradural extramedullary spinal PXA has been reported. Here, we review such a lesion occurring in a 43-year-old male who did well following gross total excision of the tumor.