Acute bleeding within a well-defined brain lesion is suggestive of cerebral cavernous venous malformation, commonly known as cavernous hemangioma or cavernoma, which is a common cerebral vascular malformation, usually with characteristic appearances on MRI. Cavernous malformations of the brainstem are uncommon, but the natural history appears to be worse than those in other locations. Retrospective annual hemorrhage rates appear to be around 5%.