抄録
A case of bifrontal cystic falx meningioma is reported, and the etiological background of cyst formation is conjectured from computed tomography (CT) scan and immunochemical findings. A 58-year-old female was admitted in May, 1983, because of an episode of generalized convulsion. Preoperative diagnosis of cystic meningioma (Nauta's type 2) was made by neuroradiological examinations. Most of the reported cases of Nauta's type 2 cystic meningioma revealed solid enhancement and delicate ring-like enhancement in CT scan and a less vascular mass on cerebral angiography. In surgery, a tumor was found adherent to the falx with bifrontal intratumoral cysts. Histological examination revealed meningotheliomatous meningioma. Microscopic examination disclosed abundant deposition of eosinophilic and hyaline-like substances in the interstitial area and tumor cells. These substances were periodic acid-Schiff negative and Alcian-blue positive, and contained immunoglobulin G. It was the authors' impression that these substances were secreted from the tumor cells, and consequently the tumor formed an encapsulated cyst.
