Abstract
Microcystic meningioma is a rare meningioma subtype that is sometimes confused with glioma or metastatic brain tumor. We report a case of a microcystic meningioma, which was undiagnosable preoperatively. A 65-year-old woman was admitted to our hospital because of gait and memory disturbances. A CT scan disclosed a low density lesion in her right frontotemporal lobe with a massive perifocal edema. The lesion demostrated as a hypointense mass on T1-weighted MRI and as a hyperintense mass on T2-weighted MRI. Contrast-enhanced MRI showed slight and heterogeneous enhancement of this tumor without dural tail sign. The external and internal carotid angiograms failed to reveal either tumor feeding arteries or tumor stain. At the time of surgery, the tumor was not adhered to the dura mater. A part of this tumor mass involved the frontal lobe arachnoid membrane, which suggested that the tumor derived from the arachnoid membrane. The pathological findings confirmed the diagnosis of microcystic meningioma. Microcystic meningioma often lacks the typical radiological findings of meningioma. It is only the characteristic MR findings, the so-called ‘faint reticular enhancement’ that may help us to make a correct preoperative diagnosis.
