Endodermal Cyst of the Third Nerve in a Child

Endodermal cysts, also known as neurogenic, neuroenteric, foregut, bronchogenic, respiratory, epithelial, teratomatous, or gastrocytoma cysts, can be found in the central nervous system, predominantly in the subarachnoid space of the cervical and thoracic spinal cord. We describe a child with an endodermal cyst of the third nerve and highlight neuroimaging findings, pathological correlation, clinical course, and patient management.

Photo Essay Section Editor: Timothy J. McCulley, MD Endodermal Cyst of the Third Nerve in a Child Kim Jiramongkolchai, MD, Muhammed T. Bhatti, MD, Herbert E. Fuchs, MD, PhD, Thomas E. Cummings, MD, Pawina Jiramongkolchai, MD, Mays A. El-Dairi, MD FIG. 1. Extraocular motility reveals adduction and supraduction deficits of the left eye. There is also limited infraduction of the left eye (not shown). Abstract: Endodermal cysts, also known as neurogenic, neuroenteric, foregut, bronchogenic, respiratory, epithelial, teratomatous, or gastrocytoma cysts, can be found in the central nervous system, predominantly in the subarachnoid space of the cervical and thoracic spinal cord. We describe a child with an endodermal cyst of the third nerve and highlight neuroimaging findings, pathological correlation, clinical course, and patient management. Journal of Neuro-Ophthalmology 2017;37:311-313 doi: 10.1097/WNO.0000000000000443 © 2016 by North American Neuro-Ophthalmology Society A 3-year-old girl was referred for evaluation and management of ophthalmoplegia and ptosis of the left eye associated with new and worsening headaches. The child was born at full term to a healthy G1O1 mother and had a normal developmental history. At the age of 2 years, she developed acute episodes of headaches associated with Departments of Ophthalmology (KJ, MTB, ME-D), Neurology (MTB), Neurosurgery (HF) and Pathology (TEC), Duke University Medical Center, Durham, North Carolina; and Department of Otolaryngology (PJ), Washington University School of Medicine Otolaryngology, St. Louis, Missouri. Presented in an oral case presentation at the Frank B. Walsh Session at the North American Neuro-ophthalmology Society Meeting, February 11-16, 2012, San Antonio, TX. The authors report no conflicts of interest. M.E.-D. is a consultant for Prana pharmaceuticals and is a recipient of the Knights Templar Foundation Award (7/2015-7/2016); M.T.B. is a speaker and consultant for Novartis Pharmaceuticals; K.J. is the recipient of the Heed Research Fellowship Award (7/2015-7/2016). Address correspondence to Mays A. El-Dairi, Department of Ophthalmology, Duke University Eye Center, DUMC 3802, Durham, NC 27710; E-mail: [e-mail] Jiramongkolchai et al: J Neuro-Ophthalmol 2017; 37: 311-313 nausea and vomiting. She was seen by her pediatrician who noted left upper eyelid ptosis and pupillary miosis. She had an initial workup for Horner syndrome including MRI, which revealed an 8 · 6 · 7 mm cyst anterior to the midbrain. Over the next 4 months, the ptosis resolved spontaneously, and there was no further report of an abnormal pupil. At the age of 3 years, she had minor head trauma followed by episodes of headaches and vomiting every 3 days. She was given amitriptyline for presumed migraine. The headaches resolved over 6 weeks of treatment but her mother then noticed abnormal movements of the left eye and recurrence of the left ptosis. Our examination revealed 2 mm ptosis of the left upper eyelid, and anisocoria that was variable with gaze. In primary position, the left pupil was larger than the right, and the difference was more accentuated in light. However, the anisocoria reversed on left gaze as the left pupil became smaller. There was no relative afferent pupillary defect. Extraocular motility showed complete adduction, infraduction, and supraduction deficits of the left eye (Fig. 1). The rest of her ophthalmic examination including vision, confrontation visual fields, anterior segment, and ophthalmoscopy were normal. Brain MRI showed a cystic lesion anterior to the left side of the midbrain (Fig. 2.). This appearance was unchanged from MRI obtained 1 year earlier. The differential diagnosis included a variety of cysts including Rathke cleft, colloid, arachnoid, endodermal, epidermoid, inflammatory, ependymal, and a cystic neoplasm. Endodermal cysts, because of their high protein content, often appear hyperintense relative to cerebrospinal fluid (CSF) on T1 and T2 MRI, with rim enhancement of 311 Copyright © North American Neuro-Ophthalmology Society. Unauthorized reproduction of this article is prohibited. Photo Essay FIG. 2. Endodermal cyst (arrows) is present on postcontrast axial (A) and coronal (B) T1 MRI as well as on axial (C) and coronal (D) T2 scans. the cyst on postcontrast images (1). In addition, a lobulated contour favors an epidermoid cyst, whereas a smooth contour is more suggestive of an endodermal cyst (2). In our patient, MRI findings were likely those of an endodermal cyst. Over the next 6 months, the patient continued to have episodes of headaches and vomiting although her ophthalmic examination was unchanged. A craniotomy was performed FIG. 3. The cyst is composed of fibrocollagenous tissue lined by a single layer of cuboidal and columnar epithelium (hematoxylin and eosin, ·20). 312 and the cyst appeared thick-walled, lying inferolateral and adherent to the left third nerve. At excision, the lesion contained thick yellow fluid, while histologic sections showed a cystic space lined by a single layer of cuboidal and columnar epithelium (Fig. 3). Over the ensuing 3 months, the patient's ocular motility improved but then worsened. Brain MRI showed increased size of the endodermal cyst to 9 · 9 mm with a 2-mm ovoid out-pouching and increased brainstem compression. The parents declined a second surgical procedure. Four years later, the patient had partial left ptosis with only slight ability to adduct and infraduct her left eye while left abduction was full. The left palpebral fissure widened on attempted right gaze. A follow-up brain MRI showed that the cyst was slightly smaller in size at 7 · 7 mm. Strabismus surgery was recommended but declined. Intracranial endodermal cysts are rare, but are reported to more often occur in the posterior fossa, anterior brainstem, and suprasellar region (3,4). These are developmental cysts which are lined by columnar epithelium of presumed endodermal origin (5). Because of the proteinaceous content, endodermal cysts usually appear hyperintense to CSF on T1, T2, and fluid-attenuated inversion recovery images (2). Determining the correct diagnosis may require correlation of radiographic appearance, histology, and immunohistochemistry (6). Jiramongkolchai et al: J Neuro-Ophthalmol 2017; 37: 311-313 Copyright © North American Neuro-Ophthalmology Society. Unauthorized reproduction of this article is prohibited. Photo Essay Complete surgical excision of an endodermal cyst is recommended to prevent recurrence. However, the proximity of the endodermal cyst to the third nerve in our patient made complete surgical excision impossible (1,4). Fenestration and drainage of the cyst is an alternate surgical strategy (6). Regardless, patients and their families should be counseled of the increased risk of recurrence with incomplete excision and the potential need for additional surgery (7). STATEMENT OF AUTHORSHIP Category 1: a. Conception and design: K. Jiramongkolchai, M. ElDairi, and M. T. Bhatti; b. Acquisition of data: H. Fuchs, T. E. Cummings, and M. El-Dairi; c. Analysis and interpretation of data: K. Jiramongkolchai, M. T. Bhatti, H. Fuchs, T. E. Cummings, P. Jiramongkolchai, and M. El-Dairi. Category 2: a. Drafting the manuscript: K. Jiramongkolchai, P. Jiramongkolchai, and M. ElDairi; b. Revising it for intellectual content: K. Jiramongkolchai, M. T. Bhatti, H. Fuchs, T. E. Cummings, P. Jiramongkolchai, and M. ElDairi. Category 3: a. Final approval of the completed manuscript: K. 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