Encapsulated intracerebral hematomas: a defined entity. Case report.

Encapsulated intracerebral hematoma is an interesting and not widely appreciated entity. It can be defined as an intraparenchymal hematoma found in normotensive patients, usually caused by histologically confirmed vascular malformations, characterized by a gradual clinical onset, and presenting a well-defined capsule at operation. One case is presented and 25 previously reported cases are reviewed, all reflecting the above-mentioned characteristics. The hematomas reviewed here occurred in relatively young patients with a mean age of 35 years and a clear male predominance (19 males, seven females). A ring of contrast enhancement around a lesion of variable density, usually with mass effect and perifocal edema, is the most relevant feature on computerized tomography. Findings on magnetic resonance images are described for the first time in the reported case. A vascular malformation was the most frequent cause found on histological examination (12 of the 26 total cases). No proven cause was found in the remaining 14 cases, although a small vascular malformation, destroyed or thrombosed after rupturing and bleeding, is the most likely etiology in these patients.