嚢胞壁内に血腫を合併したくも膜嚢胞の1例

Arachnoid Cyst with Hematoma in the Cyst Wall

I．はじめに

　くも膜嚢胞には慢性硬膜下血腫が合併し易いがその発症機序については必ずしも明確ではない．今回，われわれは中頭蓋窩くも膜嚢胞外壁内に血腫を合併した症例を経験した．本病態の発症機序を含め若十の文献的考察を加えたので報告する．

It is well known that arachnoid cysts can be associ-ated with chronic subclural hematoma. We report a case of an arachnoid cyst in which the hematoma was lo-cated in the cyst wall.

A 23-year-old male was found by chance to have an arachnoid cyst in the left middle fossa. We followed him up, because he had no symptoms. Two years after the initial examination, he began to complain of severe headache. MR image showed a hematoma located in the anterolateral space of the cyst.

On operation, we found that arachnoid membranes had covered the hematoma. We removed the hematoma and tore the inner wall of the cyst so that cerebrospinal fluid in the cyst could flow easily into the basal cistern.Pathological examination revealed arachnoid-like tis-sues outside the hematoma capsules.

Since the hematoma was wrapped all over by arach-noid tissues, it was considered that the hematoma was located in the outer wall of the cyst. About the mechanism of hematoma formation in this case, we suppose that some force could have split the outer wall of the cyst, and bloody fluid seeping through the wall membranes may have collected in the wall itself.