Lung adenocarcinoma dural metastasis at the petroclival region mimicking meningioma: a frozen-section diagnostic pitfall. Illustrative case.

BACKGROUND: Dural metastasis is a distinct entity from metastatic brain tumors with secondary dural invasion and may mimic meningioma on neuroimaging. Skull base involvement is relatively uncommon and can present a diagnostic challenge. OBSERVATIONS: A 74-year-old woman presented with left lip and tongue numbness and diplopia. MRI revealed a 21 × 16-mm homogeneously enhancing mass at the left cerebellopontine angle along the anterior petrous ridge with a dural tail sign, suggestive of a skull base meningioma. The tumor was removed via an anterior transpetrosal approach. Intraoperative frozen-section analysis suggested meningioma; however, permanent histopathological evaluation revealed dural metastasis of lung adenocarcinoma. LESSONS: Misinterpretation of the frozen-section analysis was likely caused by crush artifacts and architectural distortion that obscured glandular structures and produced meningothelial-like cellular clusters with whorl-like formations. Skull base dural metastasis can closely mimic meningioma both radiologically and intraoperatively. https://thejns.org/doi/10.3171/CASE26425.