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PubMed2026

Leptomeningeal Dissemination in TERT Promoter-mutant Anaplastic Pleomorphic Xanthoastrocytoma Responding to BRAF-MEK Inhibition: A Case Report.

Pleomorphic xanthoastrocytoma is a rare brain tumor that frequently harbors the oncogenic BRAF V600E mutation. Approximately 28.6%-47% of high-grade pleomorphic xanthoastrocytomas are associated with TERT promoter mutation and leptomeningeal dissemination, for which no established treatment exists and the prognosis remains poor. Combination therapy with BRAF and MEK inhibitors has demonstrated efficacy in BRAF V600E-mutant brain tumors. We report a case of a 22-year-old man with a right temporal lobe tumor initially diagnosed as World Health Organization grade 2 pleomorphic xanthoastrocytoma after gross total resection. Two years later, the tumor recurred and underwent malignant transformation to World Health Organization grade 3 pleomorphic xanthoastrocytoma. At the third resection, pathological and genomic analyses confirmed BRAF V600E mutation together with TERT promoter mutation. Following chemoradiotherapy, spinal leptomeningeal dissemination developed. After spinal irradiation, dabrafenib plus trametinib was initiated, resulting in partial radiological response and symptomatic improvement. Although regrowth occurred 10 months after initiation of targeted therapy, the patient remains alive at the time of writing. Here, we report a case of recurrent anaplastic BRAF V600E-mutant pleomorphic xanthoastrocytoma with leptomeningeal dissemination that showed a transient but clinically meaningful response to combined BRAF-MEK inhibition and spinal radiation therapy. In addition, this case raises the possibility of an association between TERT promoter mutation and leptomeningeal dissemination, although further studies are required to clarify this relationship.

BRAF V600E↗

PubMed2026

Spindle Cell Predominant Anaplastic Pleomorphic Xanthoastrocytoma (WHO Grade 3) With Focal Piloid Features: A Rare Case Study With Comprehensive Molecular Profiling.

Pleomorphic xanthoastrocytoma (PXA) is a rare astrocytic tumor of the central nervous system. The typical form demonstrates relatively low-grade histologic features, whereas an anaplastic variant shows more aggressive behavior, including increased mitotic activity and necrotic changes. These tumors are often associated with alterations involving key growth signaling pathways and cell cycle regulatory genes, with molecular features that may resemble those seen in other high-grade astrocytic neoplasms. We describe an unusual example of an anaplastic pleomorphic xanthoastrocytoma showing focal piloid differentiation. The patient presented with acute neurologic symptoms, and imaging demonstrated a large, enhancing, well-circumscribed cerebral lesion with limited surrounding edema. Histologic evaluation revealed a highly cellular astrocytic neoplasm composed of spindle-shaped cells with marked pleomorphism, including scattered multinucleated forms, brisk mitotic activity, and necrotic areas. At the periphery, regions with elongated bipolar glial cells and occasional cytoplasmic inclusions suggestive of piloid morphology were identified. Molecular analysis demonstrated an activating alteration in the mitogen-activated protein kinase (MAPK) pathway along with additional genomic abnormalities, while mutations commonly associated with diffuse gliomas were not detected. The presence of piloid features within an otherwise anaplastic tumor is rare and may be relevant to the relatively favorable outcome observed during extended follow-up.

anaplastic↗

PubMed1979

Pleomorphic xanthoastrocytoma: a distinctive meningocerebral glioma of young subjects with relatively favorable prognosis. A study of 12 cases.

Twelve cases of a distinctive form of supratentorial astrocytoma occurring in young subjects (ages 7 to 25) are reported. The tumors were superficial and involved the leptomeninges extensively. The tumor cells display marked pleomorphism, including bizarre giant cells and a number of mitotic figures, but no necrosis. Many contain large amounts of lipid in their cytoplasm and are surrounded by reticulin fibers, thus simulating a mesenchymal tumor. For these reasons, some examples of this tumor have been previously interpreted to represent meningocerebral fibrous xanthomas. Immunoperoxidase technique performed in nine of the twelve cases has, however, established the presence of glial fibrillary acidic protein in the tumor cells, which are therefore considered to be astrocytic. By electron microscopy many tumor cells are surrounded by basal laminae, accounting for the abundant reticulin network demonstrable in silver preparations. Since subpial astrocytes are known to be partly covered by a basal lamina, it is likely that they are the cells of origin for this neoplasm. In contrast to its pleomorphic cytology, the biological behavior of this tumor appears to be relatively favorable, and long survival times (up to 25 years) have been recorded in some cases. (These tumors are distinct from intracranial fibrous xanthomas of mesenchymal derivation. Cells of the latter are negative on GFAP stain.)

Adolescent↗