Cavernous Angiomaに合併した慢性被膜化血腫—症例報告と文献的考察

Chronic Encapsulated Intracerebral Hematoma Associated with Cavernous Angioma—Case report and review of the literature

I．はじめに

　一般に脳内出血は急激な症状で発症することが多いが，出血部位や血腫の大きさによっては，長い期間無症状に経過した後，被膜化された占拠性病変として徐々に症状を呈するものがある．これらは慢性被膜化血腫と呼ばれ，現在までに25例の報告がある^{1,2,4,5,7-13,15,16,18）}．今回われわれは前頭葉皮質下に発生した慢性被膜化血腫の1例を経験し，これまで記載の少なかったMRIやMR angiographyに関して有用な所見を得ることができ，また被膜の形成機序について病理組織学的に検討したので報告する．

We reported a case of chronic encapsulated intracere-bral hematoma associated with cavernous angioma.

A 71-year old female was admitted with a history of frontal headaches at intervals of about 3 months for the last one year. Plain CT scan showed a round mass of heterogeneous high density in the left medial frontal lobe. The outer surface of the mass was enhanced with contrast material. MRI demonstrated the mass as a high signal intensity on T1-weighted image and low intensity with laminated structure on T2-weightecl image. MR angiogram depicted the mass as a mottled high signal in-tensity. The left internal carotid artery angiogram re-vealed no abnormal shadows and vessels. These findings suggested some form of a thrombus although its under-lying pathogenesis was unclear. On January 20, 1992, a bifrontal craniotomy was performed. A whitish well-demarcated mass was seen in the left cingulate gyrus through a small corticotomy. We could not identify any branches feeding the mass. The cross-section of the mass disclosed a uniform thrombus encapsulated by a thick wall. Histological studies of the wall confirmed a caver-nous angioma within the outer collagenous layers. Chronic encapsulated hematoma, which was first re-ported by Hirsh in 1981, has represented a separate enti-ty and 25 such cases have been documented in the litera-ture. These reports suggested that the compression and/ or destruction of the surrounding tissue caused by the hemorrhage would mask the existence of the cavernous angioma or vascular malformation. If an encapsulated hematoma were encountered during an operation, surgeons should pay attention not to overlook the re-sidual capsule encompassing the cavernous angioma or vascular malformation.