Abstract
BACKGROUND AND OBJECTIVE
Cavernomas are well-circumscribed and multilobulated vascular malformations that can occur nearly anywhere in the body. Cavernomas are found 80% supratentorially, 15% in posterior fossa and only 5% in the spinal cord. Spinal cavernomas are most commonly intramedullar. Purely epidural spinal cavernoma constitute of less than 4% of all spinal epidural lesions. We report a case of histopathologically confirmed epidural cavernoma of the thoracic spine.

CASE PRESENTATION
A 24-year-old woman presented with a 6-month history of progressive chronic upper back pain. Physical examination revealed no neurological deficit. Her VAS pain scale was 6/10. Conservative treatments did not relieve her symptoms.
Thoracal MRI without contrast shown a lesion that hyperintense on T2-weighted images and isointense on T1-weighted images. The lesion sized 14x13x7 mm at T5 vertebral level located at posterolateral spinal canal. Thoracal MRI with contrast showed extradural mass with homogenous contrast enhancement. The mass was located at left posterolateral spinal canal suspected extradural meningioma.
The surgery was done via posterior approach. Left hemilaminectomy was done at T4-T5 vertebral level. Reddish soft tissue mass was observed at the epidural space. The mass was well defined and there were no signs of bony invasion. Gross tumor removal was done under the microscope. Histopathological examination of the mass showed large dilated vessel filled with erythrocyte and lined by endothelium which support the diagnosis of cavernoma. After the surgery, her pain symptom was improved.

CONCLUSION
Spinal epidural cavernomas are rare, but it should be considered as one of the differential diagnosis for spinal epidural lesions. Exact preoperative diagnosis is hard because there are no pathognomonic MRI findings of spinal epidural cavernoma. Total surgical resection of the lesions was the treatment of choice in symptomatic patients to prevent progressive neurological deficit and prospective hemorrhage.

Key words: cavernoma, spine, epidural space, surgery, MRI