Metastases from meningioma grade I are especially rare. We describe a case of a 65-year-old male with meningioma WHO grade I with a history of local recurrence and distant metastasis to the lung 26 years after the initial surgery. The original tumor was localized at the occipital low convex and invaded into the venous sinus and posterior cranial fossa; it was resected. About 15 years later, the tumor recurred in the posterior cranial fossa and γ-knife radiosurgery was performed. About 4 years later, the recurred tumor was resected at our hospital. Another 7 years later, the tumor recurred in the same area and right middle cranial fossa. All tumors except that inside the venous sinus were excised. All specimens obtained were classified as meningioma WHO grade I. Preoperative examination of the third operation revealed a nodule in the lower lobe of the right lung. The nodule grew gradually. Four months after the third surgery, partial resection of the right lung was performed. Histology indicated meningioma WHO grade I. The two lesions in the cranium and lung lesions were subjected to fluorescence in situ hybridization of the NF2 gene, and the three specimens had similar findings, genetically confirming them to be metastases of the intracranial meningioma. A literature review of past cases of meningioma progression revealed that the mean duration to metastasis is 12.5, 6.8, 3.7 years for grades I, II, and III, respectively. The current case therefore has an extended time frame.
Keywords: WHO grade I; extracranial metastasis; lung; meningioma; sinus invasion.
© 2019 The Japan Neurosurgical Society.