Rapidly growing microcystic meningioma of the middle fossa floor. Case report

A 74-year-old woman presented with a microcystic meningioma which manifested as mental disturbance. A rapidly growing tumor in the left middle fossa had not been detected by examination 10 months before. The tumor was remarkably enhanced by contrast medium on both computed tomography and magnetic resonance imaging and was associated with massive perifocal edema. Cerebral angiography revealed that the tumor was mainly fed by the left middle meningeal artery, which was embolized preoperatively. The tumor was completely removed and no postoperative adjuvant therapy was administered. The histological diagnosis was microcystic meningioma with many mitotic figures and a MIB-1 labeling index of 12.8%. Four months later, the tumor recurred and invaded the paranasal sinus. Focal irradiation successfully controlled further regrowth. This case suggests that microcystic meningioma may have aggressive features, and close observation is necessary even after gross total removal.