Infiltration of Benign Meningioma into Sagittal Sinus and Subsequent Metastasis to Lung: A Case Report and Literature Review.

BACKGROUND: Meningioma is an intracranial tumor frequently encountered in the neurosurgical setting. Extracranial disease is a rare occurrence, with a reported incidence in 0.1% of cases. Metastasis is associated with previous craniotomy, venous sinus invasion, local recurrence, and World Health Organization (WHO) grade Ill tumor. Metastasis of a benign, grade I meningioma is extraordinarily rare. CASE DESCRIPTION: We report a case of a 41-year-old with a WHO grade I intracranial meningioma that had invaded and occluded the superior sagittal sinus. Chest computed tomography (CT) scan revealed pulmonary nodules, which were biopsied and confirmed benign meningioma. The metastatic meningiomas were found before resection of the primary tumor, suggesting direct seeding through the venous system versus iatrogenic seeding. Thirteen years later, an additional lung mass was found incidentally on abdominal CT scan for workup of a sarcoidosis. Biopsy and subsequent resection confirmed benign meningioma. A retrospective review of earlier chest CT scans revealed a small lesion that corresponded to the larger lesion found 13 years later. CONCLUSIONS: This a rare case of a WHO grade I meningioma involving the sagittal sinus with direct seeding of the pulmonary vascular bed leading to multiple meningioma metastases. The report highlights an increased risk of distant metastases for a benign meningioma with invasion of dural sinuses.