Chronic encapsulated hematomas in the brain.

Two cases, one of a chronic encapsulated intracerebral hematoma occurring in a 43-year-old man and the other of an intracerebellar hematoma in an 8-year-old boy, are reported. In both cases CT scans revealed an encapsulated lesion containing the hematoma, but angiographic pictures were poor except for revealing a space-occupying lesion and a small vascular lesion. Both hematomas were successfully removed. Each case was associated with a thick, fibrous capsule that was found histologically to arise from an occult angiomatous malformation. The encapsulated hematomas partially included old thromboses, and both old and recent areas of hemorrhage. The latter were considered to be due to the rupture of vessels developed near the inner surface of the thickest part of the fibrous capsule. Although the condition is uncommon, chronic hematoma must be considered when encapsulated mass lesion is present in the brain.