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| LETTER TO EDITOR |
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| Year : 2013 | Volume
: 61
| Issue : 5 | Page : 563-565 |
Interhemispheric neurenteric cyst
Mazda K Turel, Geeta Chacko, Ari G Chacko
Department of Neurological Sciences, Christian Medical College, Vellore, Tamil Nadu, India
| Date of Submission | 13-Oct-2013 |
| Date of Decision | 24-Oct-2013 |
| Date of Acceptance | 24-Oct-2013 |
| Date of Web Publication | 22-Nov-2013 |
Correspondence Address:
Mazda K Turel
Department of Neurological Sciences, Christian Medical College, Vellore, Tamil Nadu
India
 Source of Support: None, Conflict of Interest: None  | Check |
DOI: 10.4103/0028-3886.121959
How to cite this article:
Turel MK, Chacko G, Chacko AG. Interhemispheric neurenteric cyst. Neurol India 2013;61:563-5 |
Sir,
Neurenteric cysts within the central nervous system (CNS) are rare congenital lesions most commonly located in the spine or posterior fossa. Supratentorial neurenteric cysts are distinctly infrequent, only 30 cases including two cases in the interhemispheric fissure have been reported. [1],[2],[3]
An 18-year-old girl from the Andamans presented with progressive episodic headache with blurring of vision at the peak of the headache of 1 year duration. Ocular examination showed papilledema. There were no other neurological deficits. Magnetic resonance imaging (MRI) [Figure 1] showed a 7 cm × 5 cm × 4 cm intradural, extraaxial, cerebrospinal fluid (CSF) intensity, non-enhancing right parietal cystic lesion with linear extension parasagittally into the interhemispheric fissure. The cyst was hypointense on T1 and hyperintense on T2 weighted images, showed no restriction on diffusion weighted imaging or blooming on susceptibility weighted images. The pre-operative diagnosis was that of an interhemispheric arachnoid cyst. At surgery, the cyst bulged into the durotomy opening and the wall was pearly white unlike the bluish appearance of a typical arachnoid cyst [Figure 2]. The cyst wall was flimsy and milky white fluid was aspirated. It could not be totally excised due to a large vein overlying it anteriorly and the capsule diffusely merged with the pia over the buckled brain surface. Cytopathology was negative for malignant cells. At histopathology [Figure 3] the cyst was lined by single layered to pseudostratified ciliated columnar epithelium, with focal goblet type of mucinous cells, with Periodic acid-Schiff stain positive secretions in their cytoplasm, resembling enteric epithelium. The wall showed focal calcification, chronic inflammatory cells and congested capillaries with other fragments showing granular amorphous, acellular, degenerated material. There was no evidence of granulomas, parasites or malignancy. These findings were suggestive of a neurenteric cyst. Postoperatively her headache completely resolved. However, she had two episodes of generalized seizures, which were controlled with anti-epileptics. She made a good recovery and was discharged without any neurological deficit. | Figure 1: (a) T2-weighted axial flair (b) T2-weighted coronal (c) T1-weighted sagittal images (d-f) axial, coronal and sagittal gadolinium enhanced images showing a well-defined non-enhancing T1 hypointense, T2 hyperintense parietal cystic lesion with extension into the interhemispheric fissure. The mass effect is minimal compared to the size of the cyst
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 | Figure 2: Intraoperative image of the parietal interhemispheric neurenteric cyst showing a white cyst wall which contained milky fluid within it
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 | Figure 3: Photomicrograph of the neurenteric cyst wall lined by ciliated columnar epithelium at (a) low power (×10) and (b) high power (×40) and (c) showing presence of mucin within it
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Neurenteric cysts are uncommon congenital cysts believed to be of an endodermal origin, though their pathogenesis within neuroectodermal tissue of the CNS is still unsubstantiated. [1] The interhemispheric location was first described by List and Williams in 1961 who proposed that this dysembryonic lesion had a preference for the midline and was similar in pathology to its counterparts found in the roof of the third and fourth ventricle. They hypothesized that this occurs at a very early embryonic stage where the ectodermal cells have not yet differentiated and retain their pluripotent character. However, this theory cannot explain the more laterally placed supratentorial neurentic cysts. Mittal et al. [1] proposed that anomalous endodermal migration dorsally through the primitive neurenteric canal to the ectoderm can freely travel cephalad and more lateral resulting in the latter entity, thus also accounting for the progressively decreasing number of intraspinal, posterior fossa and supratentorial neurenteric cysts.
Despites its advances, radiology cannot provide an accurate diagnosis [Table 1]. Our cyst had all the radiological features of a typical arachnoid cyst. Prothmann et al. [4] have suggested the use of constructive interference in steady state sequences for these lesions where the cysts are slightly hypointense compared with CSF, but still hyperintense to brain tissue. Occasionally these lesions can mimic cystic tumors, but the latter generally show some enhancement of the cyst wall. Computed tomography (CT) may show some peripheral calcification and remodeling of the overlying bone in long standing cases.
Parasitic cysts, mainly hydatid also follow similar appearances on MRI but there can be subtle changes in the CSF intensity depending upon its protein content or whether it was infected or ruptured. [5] Hydatid cysts are usually intraparenchymal, and though the subarachnoid space is another common site of involvement to our knowledge it has not been reported to occur in the interhemispheric fissure. According to Osborne and Preece, the pericyst is usually visible as a separate peripheral capsule of the cyst radiologically. [6]
At surgery, neurenteric cysts may be smooth, thinned walled and transparent mimicking an arachnoid cyst or it could be thicker and opaque making it difficult to differentiate from a hydatid cyst [Figure 2]. The contents also vary from being clear to mucoid to milky to xanthochromic. Since the operative strategies in the treatment of these cysts-arachnoid, hydatid and neurenteric cyst is very different it might be prudent to send an intraoperative analysis of the fluid to guide further management.
| » References | |  |
| 1. | Mittal S, Petrecca K, Sabbagh AJ, Rayes M, Melançon D, Guiot MC, et al. Supratentorial neurenteric cysts-A fascinating entity of uncertain embryopathogenesis. Clin Neurol Neurosurg 2010;112:89-97. 
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| 2. | Pulido-Rivas P, López-García A, Jiménez-Heffernan J, Sola RG. Intracerebral neurenteric cysts in newborn infants. Rev Neurol 2012;55:26-30.
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| 3. | Little MW, Guilfoyle MR, Bulters DO, Scoffings DJ, O'Donovan DG, Kirkpatrick PJ. Neurenteric cyst of the anterior cranial fossa: Case report and literature review. Acta Neurochir (Wien) 2011;153:1519-25.
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| 4. | Prothmann S, Trampel R, Fritzsch D, Schneider JP. Intracranial neurenteric cysts. Rare incidental findings with typical MR signal characteristics. Eur J Radiol Extra 2010;74:41-5.
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| 5. | Mohindra S, Savardekar A, Gupta R, Tripathi M, Rane S. Varied types of intracranial hydatid cysts: Radiological features and management techniques. Acta Neurochir (Wien) 2012;154:165-72.
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| 6. | Osborn AG, Preece MT. Intracranial cysts: Radiologic-pathologic correlation and imaging approach. Radiology 2006;239:650-64.
[PUBMED] |
[Figure 1], [Figure 2], [Figure 3]
[Table 1]
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