An intra-axial wolf in extra-axial clothing: A rare case of high-grade astrocytoma and literature review

Background: High-grade astrocytomas are typically intra-axial, diffusely infiltrating brain tumors. Their presentation as a primary dural-based, extra-axial mass mimicking an aggressive meningioma is exceptionally rare, creating a significant diagnostic challenge and potential for preoperative misdiagnosis. Case Description: A 40-year-old male presented with a 2.5-year history of headache and vertigo, followed by generalized seizures. Neurological examination revealed bilateral papilledema with subtle right-sided upper motor neuron signs. Imaging revealed a large, heterogeneously enhancing, left fronto-temporo-parietal mass with broad dural attachment, calvarial erosion, and mass effect, but notably minimal perilesional edema. The primary radiological differential diagnoses included atypical meningioma, dural-based lymphoma, and metastasis. Following maximal safe resection, histopathological and molecular analysis confirmed the diagnosis of an astrocytoma, isocitrate dehydrogenase (IDH)-mutant, central nervous system World Health Organization grade 4. The patient received adjuvant focal radiotherapy (59.4 Gy in 33 fractions) and at 6-month follow-up was neurologically stable, seizure-free, and demonstrated marked radiological regression. Conclusion: This case highlights that high-grade astrocytoma, including IDH-mutant variants, can present with classic extra-axial and meningioma-like imaging features. It underscores the critical importance of definitive histomolecular diagnosis over radiographic impression alone to guide appropriate, biology-directed management. The patient demonstrated an encouraging early clinical and radiological response following surgical resection and radiotherapy.