Meningioma cysts.

We studied six cases of intracranial meningioma with cyst formation. Manifestations included focal neurologic signs (four cases), seizures (three cases), headache (three cases), and personality changes (two cases). CT revealed a cystic enhancing supratentorial lesion in five cases. Angiographic changes of meningioma were observed in only three cases, and correct preoperative diagnosis was made in only half the cases so studied. Histologically, all lesions were syncytial meningiomas. Cyst fluid was always xanthochromic, acellular, and highly proteinaceous. The variety of anatomic configurations suggests several pathophysiologic mechanisms in formation of the cysts that are commonly misdiagnosed preoperatively. Tissue analysis is needed for all cystic, enhancing lesions of the brain.