頭蓋外髄膜腫Extracalvarial Meningiomas

EXTRACALVARIAL MENINGIOMAS

Ｉ．はじめに

　頭蓋内髄膜腫の頭蓋外への進展および頭蓋外転移，眼窩・脳神経孔・脊髄に関係した髄膜腫を除いたいわゆる頭蓋外髄膜腫（extracalvarial meningiomas）の発生頻度はきわめて少ない。われわれは昭和16年から昭和43年までの28年間に組織学的に証明しえた髄膜腫226例を経験しているが，上記の意味での頭蓋外髄膜腫は2例しかなかつた。本邦では，われわれの知る限りでは三輪ら^17）が1例を第8回日本神経病理学会に報告しているにすぎない。われわれの2例に若干の文献的考察を加えて報告する。

We have presented two cases of extracalvarial meningiomas, the one arising from the external sur-face of the skull and the other from the ethmoidal sinus, without demonstrable dural attachment. Histo-logically, both were meningocytic meningiomas. Ex-cept for extracranial extension and extracranial metastasis of intracranial meningiomas, and those related to the orbit, cranial nerve foramina and spinal cord, extracalvarial meningiomas are rare. Two cases presented here are found in 226 histologically verified meningiomas experienced in the Department of Neu-rosurgery of Kyoto University Hospital from 1941 through 1968. Their incidence was O. 9%. From the review of the literature we support the conception that they probably originate from ectopias of the arachnoid cells.