Extraneural and extracranial metastatic astrocytoma with primitive neuroectodermal component: a case report.

BACKGROUND: Astrocytoma is a highly malignant tumor of the central nervous system with limited survival, despite standard multimodal therapies. While typically remains confined to the central nervous system, rare instances of extraneural and extracranial metastasis have been documented. The underlying pathophysiology remains poorly understood, with very few reported cases-particularly in tumors harboring isocitrate dehydrogenase mutations. CASE PRESENTATION: We describe the case of a 21-year-old female New Zealander of European descent with O6-methylguanine-DNA methyltransferase promoter-methylated, IDH1-R132H-mutant astrocytoma (World Health Organization 2021 central nervous system grade 4) containing a primitive neuroectodermal tumor-like component, which exhibited diffuse skeletal and leptomeningeal metastases. CONCLUSION: This case represents an unusual presentation of extraneural and extracranial metastatic spread in a young female New Zealander of European descent with an isocitrate dehydrogenase-mutant astrocytoma. Compared with recent literature, it is notable for early systemic dissemination and the coexistence of bone and leptomeningeal disease. A multidisciplinary discussion concluded that additional biopsy of metastatic sites was unwarranted owing to clear pathological correlation, clinical decline, and poor prognosis. Molecular characteristics such as cyclin-dependent kinase inhibitor 2A/2B deletion may further refine classification. A review of current literature underscores the importance of the 2021 World Health Organization classification updates and highlights potential roles for epithelial-mesenchymal transition and glymphatic dissemination in metastasis. Targeted therapies-particularly isocitrate dehydrogenase inhibitors-are under active investigation. This case reinforces the need for ongoing research into predictive biomarkers and individualized treatment strategies.