A case of neurenteric cyst of spine mimicking an arachnoid cyst.

backgroundIntradural cysts of the spine are arachnoid cysts, neuroenteric cysts, and ependymal cysts. The usual finding in case of a neurenteric cyst is a ventrally located non-contrast-enhancing lesion that is isointense on T1-weighted sequence and hyperintense on T2-weighted imaging. An arachnoid cyst is hypointense in T1-weighted image and hyperintense in T2-weighted image, mimicking cerebrospinal fluid(CSF), and the location is dorsal to the cord. But a neurenteric cyst can mimic an arachnoid cyst in appearance. CASE: A 48-yr old autorikshaw driver presented with weakness of fingers and lower limbs. All sensations were decreased below xiphisternum(T6). The gait was spastic. Magnetic Resonance Imaging(MRI) showed an extramedullary intradural cyst at C7-T1 level. It was hypointense on T1-weighted image and hyperintense on T2-weighted image. There was no enhancement with contrast. C7/T1 Laminectomy was done. On gentle retraction of the cord, a whitish cyst was seen. Some clear fluid was aspirated and cyst was excised en toto. Myelopathy improved over two weeks. Histopathological examination showed a cyst wall composed of fibrocollagenous tissue, and lined by pseudostratified epithelium containing many goblet cells and having focal ciliation. The findings were consistent with neurenteric cyst. Follow-up MRI after five years showed no recurrence.

conclusionTo our knowledge, the peculiarities of the case are that the radiological features mimicked arachnoid cyst in having the intensity of CSF. But the ventral location was suggestive of a neurenteric cyst. Total excision could be done through the posterior approach after decompressing the cyst by aspiration.