Intracranial cavernous angioma manifesting as subarachnoid hemorrhage--case report.

A 56-year-old male presented with a posterior fossa cavernous angioma manifesting as persistent headache with mild neck stiffness. Lumbar puncture revealed subarachnoid hemorrhage (SAH). Repeated four-vessel angiography failed to identify the source of the SAH. Magnetic resonance (MR) imaging demonstrated multiple small lesions in the posterior fossa and cerebral hemispheres, and the SAH. A mass arising from the biventral lobule of the right cerebellar hemisphere extended exophytically into the cisterna magna with intratumoral hemorrhage. These findings were compatible with the presumptive diagnosis of SAH from the mass at the right biventral lobule. The lesion was totally removed through a suboccipital craniectomy without sequelae. The histological diagnosis was cavernous angioma. Intracranial cavernous angioma presenting only as SAH has never been reported before. The use of MR imaging in establishing the diagnosis of vascular malformations is emphasized, particularly when neither computed tomography nor angiography can adequately visualize the origin of SAH.