Abstract
A case of an avascular cystic meningioma with massive perifocal edema, which was unable to diagnose preoperatively, was reported. A 60-year-old man was admitted because of presenting with minimum left hemiparesis. CT scan and MRI disclosed a round cystic mass lesion in his right parietal lobe, with ring enhancement after administration of contrast medium. The mass lesion was accompanied with massive perifocal edema. Angiogram showed no evidence of meningeal vascularization nor tumor stain. Preoperative differential diagnosis was glioblastoma or metastatic brain tumor. At surgery, a cystic tumor with an attachment to the superior sagittal sinus was removed. Xanthochromic fluid without debris was obtained from the cyst. The cyst wall was also removed. The pathological findings confirmed the diagnosis of meningotheliomatous type meningioma. Dilated capillaries were often found facing the cystic cavity, where the number of tumor cells decreased and perivascular edema was observed. A secretory phenomenon was considered to be related to the cyst formation. An isolated subarachnoid space, which was detected as a peritumoral band on MRI, existing in the surface of the frontal aspect of the tumor, was considered to be related to the extensive perifocal edema. Postoperatively, the patient had an improvement in the hemiparesis. In this report, a possible relationship between cyst formation and extensive perifocal edema in meningiomas was discussed. Peritumoral band and dural tail sign detected on MRI appeared to have a diagnostic value in a case of cystic meningioma, distinguishing it from glioblastoma or metastatic brain tumor.
