Discussion

Cavernous hemangiomas, also called cavernous angiomas, are congenital vascular malformations of unknown origin that frequently are considered to be hamartomas [1, 6, 7]. CNS cavernous hemangiomas may be solitary or multiple, may occur in conjunction with cavernous hemangiomas in other organ systems or in conjunction with capillary telangiectasis, and may appear as sporadic or familial cases [1]. These uncommon lesions may occur anywhere in the CNS. Of cavernous hemangiomas that involve the epidural space, lesions in the vertebral bodies with extension into the epidural space are much more common than are purely epidural lesions [4, 6]. Purely epidural spinal cavernous hemangiomas account for less than 4% of spinal epidural masses [4]. When they occur, they are most frequent in the thoracic or lumbar regions. Most of the reported purely spinal epidural cavernous hemangiomas were larger than the lesion in this case; many of them extended into neuroforamina, and a few of them extended into the paraspinal region. Recent articles have described the MR appearance of cavernous hemangioma in other locations, including the brain, orbit, liver, and spinal cord, but the MR appearance of a purely epidural cavernous hemangioma, to our knowledge, has not been reported.

Spinal epidural cavernous hemangiomas may be manifested as back pain, as a radiculopathy simulating a disk protrusion, as an insidious progressive paraparesis, or as acute paraplegia. Trauma may precipitate the patient's symptoms, often producing a radiculopathy that is confused with an acute disk herniation [4-6]. Thus, the presenting symptoms in our patients were typical but nonspecific. In the present case, the spinal epidural cavernous hemangioma appeared as an epidural mass on a myelogram, as a subtle ill-defined mass on CT scans, and as a well-circumscribed mass on MR images. T1-weighted MR images showed a mass with intermediate signal intensity similar to that of CSF and peripheral enhancement. T2-weighted images showed a mass with mildly heterogeneous high signal intensity slightly less than that of CSF and a surrounding lowintensity rim. The cause of this low-intensity rim was not clear, as the resected specimen showed only a small amount of diffusely scattered hemosiderin and no calcification. Diagnostic considerations based on appearance and location included a spinal meningeal cyst or a metastatic lesion. Neuroma, neurofibroma, and meningioma were considered because of the location, but the MR appearance of the lesion made these unlikely. This case shows one MR appearance of a spinal