Spinal Dermoid Cyst: Characteristic CT Findings after Metrizamide Myelography

Abstract

A 25-year-old male complained of intermittent, sharp pains about the left eye and in the left side of the chest. Neurological examination revealed paresthesia and impaired perception of touch and pin-pricks in the dermatomes of Th8 and Th9 on the left side. In all four extremities, the muscle stretch reflexes were equal and slightly hyperactive, without weakness or sensory deficits. Metrizamide myelography showed defective filling at the level between the upper 8th and 9th thoracic vertebrae. The lesion was also demonstrated by computed tomography (CT) scan performed 1 hour later, appearing as an oval, radiolucent mass in the left dorsal spinal canal, which compressed the spinal cord forward and toward the right. Serial sections of the spinal canal revealed the lesion to be partly filled with contrast medium. Repeat CT scan 24 hours after metrizamide myelography showed more contrast medium in the periphery of the lesion, giving it a doughnut-shaped appearance. At surgery a smooth-surfaced cyst containing sebum and white hair was totally removed from the intradural extramedullary space. The histological diagnosis was dermoid cyst. There have been a few reported cases of intracranial epidermoid cyst in which filling of the cyst was suggested on metrizamide CT myelography. These findings may complicate the differential diagnosis of arachnoid cyst and dermoid or epidermoid cyst when only CT is used.