[Chronic encapsulated intracerebral hematoma associated with cavernous angioma: case report and review of the literature].

We reported a case of chronic encapsulated intracerebral 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-weighted image. MR angiogram depicted the mass as a mottled high signal intensity. The left internal carotid artery angiogram revealed no abnormal shadows and vessels. These findings suggested some form of a thrombus although its underlying 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 cavernous angioma within the outer collagenous layers. Chronic encapsulated hematoma, which was first reported by Hirsh in 1981, has represented a separate entity and 25 such cases have been documented in the literature. 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 residual capsule encompassing the cavernous angioma or vascular malformation.