Extraaxial cavernous hemangioma with hemorrhage.

Intracranial cavernomas, initially described as rare lesions [1], have been seen with increasing frequency since the advent of MR imaging [2-5]. MR features of cavernomas are highly suggestive of the diagnosis, although not pathognomonic. Cavernomas are classically intraparenchymal lesions and occult to angiography. They have a pseudotumoral growth [6] and a low potential for life-threatening hemorrhage, at least in supratentorial locations [7]. We report a case of a vascular lesion in an atypical location that was identified as a cavernous hemangioma. The lesion arose in the perimesencephalic cistern, and was accompanied by symptoms of acute onset of diplopia and meningeal signs. Extracerebral cavernous hemangiomas, as reported in the literature, have slightly different clinical, angiographic, and surgical features compared with intraparenchymal lesions, and can easily be misdiagnosed as meningioma unless MR imaging is performed.