Hemangiomas in the epidural space are rare. They are not considered true vascular neoplasms but are generally classified as hamartomas or vascular malformations. These lesions represent about 4% of epidural masses. Most reports detail the pathological and imaging characteristics of the cavernous type hemangioma. They are lobular masses with homogenous T2 hyperintensity with enhancement1. The main differential diagnosis for these lesions are schwannoma, meningioma, granulomatous inflammation, disc herniation, and epidural hematoma or seroma. Surgical management of these different lesions is critical and varied; therefore, proper preoperative planning is of utmost importance.

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Figure 1. MR imaging revealing abnormal enhancement dorsal to the T5 level, approximately 3.3 cm in maximal transverse and 1.8 cm in maximal anterior posterior dimension.

A 62 year-old female s/p laminectomy at an outside hospital presented with progressive numbness in a bandlike distribution in the mid-thoracic region and signs of myelopathy. Her back pain consisted of sharp, shooting pain along with a deep ache and pressure feeling when lifting, pulling, pushing, and moving. On exam, her extremities were of normal bulk, tone and contour with 5/5 power in all major muscle groups. There were no signs of pronator drift. She had myelopathy in the legs and some hyper-reflexia. MRI of thoracic spine was significant for abnormal enhancement dorsal to the T5 level, approximately 3.3 cm in maximal transverse and 1.8 cm in maximal anterior posterior dimension (Fig 1a-b). It extended into the epidural space and laterally through the left T5-6 neuroforamen. The foramen was expanded, consistent with a chronic process. The mass was multilobulated and suggestive of a schwannoma, but appeared more aggressive.

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Figure 2. Low power view (40x) of thoracic tumor showing a vascular proliferation within adipose tissue composed of medium to small blood-filled vessels. A small amount of perivascular fibrous connective tissue is present. The vessels are loosely arranged in a lobular configuration. Some of the vessels ramify with each other. No calcifications, thrombosis or internal structure are noted in the vessel lumens.

The patient was taken to the operating room for lesion resection. She underwent a left T4-7 laminectomy with mass resection and T5-6 rhizotomy. Intraoperative findings were consistent with no evidence of tumor. Multiple specimens were send for permanent pathological preparation (Figs 2-4). Final pathological diagnosis on permanent sections was hemangioma in the epidural space.

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Figure 3. Medium power (100x) showing an area of increased adventitial fibrosis surrounding the thin-walled vessels. Scant fibrin is present within the vessel lumens.

There have been few previous reports of this disease entity with similar reported differential diagnosis. One report reviewed some imaging characteristics of epidural hemangiomas. The main items on their differential were similar to ours including schwannoma and granulomatous inflammation. They reported that the most common MR features of cavernous epidural hemangiomas were solid hypervascularity with a lobular contour [1]. Morioka et al reported lack of foraminal widening with these lesions [2]. However, a report by Shin et al was more in line with our findings that there was a degree of foraminal widening [4].

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Figure 4. High power view (400X) showing thin venous-like walls of the hemangioma lined by a single cell layer.

Rovira et al report two cases with similar findings of T2 hyperintensity and homogenous enhancement [3]. They report that characteristics that help distinguish this lesion from extruded disk fragments or tumors are the degree of high homogenous signal intensity on T2 imaging, their ovoid shape, and their lack of anatomic relationship to the disk or exiting nerve root. Our case did not follow this pattern in that the lesion was in very close proximity to the disk and exiting nerve root, which is one reason why we were so strongly suspecting a schwannoma.

These lesion are quite rare, but should obviously be kept in the differential diagnosis for any enhancing foraminal mass. As intraoperative hemorrhage is a definite risk, preoperative suspicion is important. These lesion are best treated with complete resection, providing both pain relief and good prognosis.

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