Clinical analysis for an unusual large cystic meningioma: Case report and review of the literature

The authors report the case of a 17-year-old boy with an unusual large cystic meningioma (Nauta type II) in the right hemisphere. The imaging appearances of this patient were very unusual. The shape of the huge cyst was crescentic and similar to subdural hematoma. It lay between the dura and the solid tumor parts. In addition there was a small intracystic nodule attached to the cyst wall. The patient underwent a right hemisphere craniotomy. At surgery it was found that the cyst contained a large amount of xanthochromic fluid and some semitransparent serumlike sediment. The intracystic nodule was proved to be necrotic substance without tissue and cell structure. Histological examination displayed an anaplastic meningioma, of which the cyst wall also consisted of meningioma tissue.To the best of the authors’ knowledge, such an unusual case of cystic meningioma has not been reported. The authors review the literature with reference to intratumoral cyst associated with meningiomas, analyze the unusual imaging appearances of this patient, and explore the mechanism of cyst formation.The mechanism of cyst formation associated with meningiomas is not perfectly understood. Intratumoral cyst formation may be attributed to microcystic degeneration, ischemic necrosis, intratumoral hemorrhage, transudation and secretory changes within the tumor.