British Journal of Radiology (2007) 80, e137-e140
© 2007 British Institute of Radiology
doi: 10.1259/bjr/31817019
Congenital cystic eye: features on MRI
R Gupta, MD
A Seith, MD
B Guglani, MD
and
T P Jain, MD
Department of Radio-diagnosis, All India Institute of Medical Sciences, New Delhi, India
Correspondence: Dr Ashu Seith, Department of Radio-diagnosis, All India Institute of Medical Sciences, Ansari Nagar, New Delhi 110029, India. E-mail: ashubhalla1{at}yahoo.com
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Abstract
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Congenital cystic eye is a rare cause of cystic orbital lesion. The condition is recognized at birth as a large orbital mass in place of a normal eye. Only 29 cases have been reported previously. We report a case of unilateral congenital cystic eye with multiple brain anomalies in the form of agenesis of corpus callosum and grey matter heterotopias. In this case report we highlight the MRI features of this entity, which have not been described previously in the literature.
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Introduction
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Congenital cystic eye is a rare anomaly resulting from partial to complete failure of the optic vesicle to invaginate [1]. Association of intracranial abnormalities with congenital cystic eye has rarely been described. We report a case of congenital cystic eye with multiple brain anomalies.
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Case report
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A 5-year-old male child presented with a left orbital mass. The mass had been present since birth and had not significantly increased in size. The child was a product of full term normal vaginal delivery. There was no history of consanguinity and siblings were healthy. No history of seizure or developmental delay was elicited. On examination, a large erythematous soft tissue mass was seen in the left orbit, stretching the upper eyelid and bulging out of the palpebral fissure. Posterior aspect of the mass was smooth, cystic in consistency and transilluminant. No globe was identified. Right eye was normal.
CT scan tailored for the orbits was performed. CT revealed a complex mass in the left orbit. The anterior component of the mass was irregular with soft tissue attenuation, which showed mild contrast enhancement. Posterior component was smooth, unilocular and cystic. No evidence of fat or calcification was seen in the mass. No lens was seen. Optic nerve and extraocular muscles were not visualized. The orbit was expanded but no bony defect was seen. The possibility of colobomatous cyst was kept but the nature of the soft tissue mass was not clear and globe was not identified.
Because of diagnostic ambiguity on CT, an MRI of the orbit and brain was carried out. On MRI, a complex mass was seen filling and expanding the left orbit. The anterior one third was irregular, appearing isointense to muscle on T1 (Figure 1a
) and heterogeneously hyperintense on T2 weighted images (Figure 1b). The posterior two thirds were smooth, homogeneous, pyriform shaped, with apex towards the optic canal. This part was homogeneously hypointense on T1 (Figure 1a) and very bright on T2 (Figure 1b), similar to vitreous/cerebrospinal fluid (CSF). Post-gadolinium images showed heterogeneous enhancement of the anterior part (Figure 1c). No intracranial communication of the cyst was seen; however, a short thin optic nerve stalk was seen arising from the posterior tip of the cyst (Figure 2a). This thin optic nerve stalk joined the contralateral optic nerve at a malformed optic chiasm (Figure 2b). No extraocular muscles were seen and no lens was identified. Imaging of the brain revealed complete agenesis of the corpus callosum (Figure 3). Grey matter heterotopia was seen in the left frontotemporal lobe and the left lateral ventricle was small (Figure 4). The absence of globe and attachment of optic nerve stalk to the cyst ruled out a possibility of microphthalmos with colobomatous cyst. Lack of intracranial communication of cyst and enhancement pattern of soft tissue mass, which was different from brain parenchyma, ruled out meningoencephalocele. A final radiological diagnosis of congenital cystic eye with agenesis of corpus callosum with grey matter heterotopia was made.
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Figure 1. (a) Axial T1 weighted (repetition time (TR) 450/echo time (TE) 14) image of the orbits shows a complex mass in the left orbit. Anterior component is isointense to muscle. Posterior cystic component is well defined homogeneous, low signal intensity similar to vitreous/cerebrospinal fluid (CSF). (b) Axial T2 weighted (TR 3000/TE 95) image of the orbits shows the soft tissue component to be heterogeneously hyperintense. The cyst appears brightly hyperintense with smooth thin walls. No normal orbital contents such as extraocular muscles or globe can be identified. (c) Axial post-gadolinium fat saturated T1 weighted image shows heterogeneous enhancement of the anterior soft tissue mass. Enhancement is much more than brain parenchyma.
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Figure 2. (a) Sagittal T2 weighted fat saturated image shows a thin hypointense optic nerve stalk attached to the tip of the pyriform cyst traversing through the optic canal. No intracranial communication of the mass is seen and the optic canal is not widened. (b) Axial fat saturated T2 weighted image shows the thin optic nerve stalk joining the right optic nerve at a malformed optic chiasm (arrow). Also noted is the lack of any area of signal loss in the soft tissue mass on fat suppression.
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Figure 3. SagittalT2 weighted (repetition time (TR) 500/echo time (TE) 96) image of the brain in the midline shows complete agenesis of corpus callosum. The cingulate gyrus is absent and there is characteristic radial arrangement of gyri along the interhemispheric fissure.
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Figure 4. Axial inversion recovery(repetition time (TR) 6490/echo time (TE) 67/inversion time (TI) 350) image at the level of sylvain fissure shows scattered areas of grey matter intensity in left frontotemporal subcortical regions. The left lateral ventricle is small. Right occipital horn is enlarged suggestive of colpocephaly.
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The mass was excised at surgery. Histopathology of the anterior soft tissue mass revealed glial hamartoma. Cyst wall was composed externally of fibrous collagenous tissue and internally of neuroglial tissue with an incomplete attempt at maturation into retinal elements. No mature globe components were seen. The diagnosis of congenital cystic eye was confirmed.
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Discussion
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Normally, invagination of the optic vesicle occurs at the fourth week of gestation. Partial or complete failure of the optic vesicle to invaginate results in congenital cystic eye.
The condition is very rare and existing knowledge is based on individual case reports. Duke-Elder reviewed the literature from 1880 to 1960 and found only 16 cases that he believed represented congenital cystic eye. It has also been called anophthalmos with cyst in the literature. The term congenital cystic eye was coined by Mann [2]. Congenital cystic eye is thought to result from non-invagination of the primary optic nerve vesicle between the 2 mm and 7 mm stages of embryonic development, and failure of ectodermal elements to develop into the future eye structures. The orbit thus contains a cyst instead of an eye. Although the exact aetiology of congenital cystic eye is not known, the frequent presence of inflammatory cells in the cyst suggests an inflammatory cause. No hereditary tendencies or abnormalities during pregnancy or the perinatal period have been described [2]. In contrast, a discontinuation in development between the 7 mm and 14 mm stage of embryonic development leads to formation of the more common microphthalmos with coloboma. Congenital cystic eye needs to be differentiated from microphthalmia with cyst. Microphthalmia with cyst develops from incomplete closure of the fetal cleft that results in a cyst attached to the sclera. The eyes are microphthalmic and frequently have uveal, retinal and lens colobomas. The cysts with microphthalmia are usually located in the inferior orbit and cause the lower eyelid to bulge. In contrast, congenital cystic eye usually causes bulging of the upper eyelid. The main differentiating point is the complete absence of globe in congenital cystic eye [3].
The cyst associated with congenital cystic eye may vary in size and may have an attached stalk. The patency of the stalk, if present, is associated with the size of the cyst. If the stalk is patent, the size of the cyst remains small due to communication of the cyst with the cranial cavity. The cyst may be partially or completely replaced by neuroglial tissue [2], as was seen in our case.
Congenital cystic eye may occur in isolation or with other malformations, such as contralateral microphthalmia with cyst and dermal appendages [1]. Non-ocular abnormalities have also been reported in association with congenital cystic eye. These include facial clefting, saddle nose, nostril malformation, choanal atresia, malformation of the sphenoid bone, multiple punched out lesions of the face and scalp, microphallus with hydrocele, hypoconvex fingernails on short stubby fingers and bifid thumb [2]. Few descriptions of intracranial abnormalities associated with congenital cystic eye exist. This may be related to the fact that many case reports of congenital cystic eye pre-date the era of sophisticated neuroimaging and the paucity of well-documented cases. The reported intracranial associations are agenesis of corpus callosum, basal encephalocele and midbrain deformity [1, 4]. Grey matter heterotopias have not been reported previously. In our patient, corpus callosum agenesis as well as grey matter heterotopias were seen. The aetiological basis of association of intracranial anomalies with congenital cystic eye is not clear due to the paucity of reported cases. The term cranial ectodermopathy has been used by some authors for this constellation of anomalies, and some have suggested an association of prosencephalic defects with that of the optic vesicle . However, these abnormalities do not provide further insight into the pathological findings [1[.
Histopathological features are well documented in the literature as surgical removal was carried out in all the reported cases. In general, the cyst is lined externally by dense fibrous connective tissue to which skeletal muscle and adipose tissue were attached. The inner aspect of the cyst was lined by neuroglial tissue, possible immature retinal tissue and cuboidal epithelium. No fully developed ocular structures can be identified [4]. Imaging features are scantily described. The few reports on imaging features of congenital cystic eye describe the appearances on CT. The usual finding is an intraorbital cystic mass which may be unilocular [5] or multilocular [2, 6]. The mass may have an enhancing soft tissue component depending on the amount of glial proliferation [1, 6]. A thin optic nerve stalk may be found [5]. Extraocular muscles are usually absent [1, 6] or hypoplastic [5]. A globe is not identified.
MRI findings of congenital cystic eye have not been described. Albernaz et al [3] described the MRI findings in clinical anophthalmos in 1997. They emphasized the documentation of absence of globe to differentiate between severe microphthalmos and anophthalmos. Anophthalmos was manifested as a lack of globe(s) with the presence of amorphous tissues hypointense on T2 weighted images suggesting fibrosis and not hyperintense as one would expect with microphthalmos, in which there is normal but reduced volume of vitreous [3].
MRI in our case not only helped in making the diagnosis of congenital cystic eye, but also detected the additional intracranial anomalies, i.e. agenesis of corpus callosum in grey matter heterotopias.
In conclusion, congenital cystic eye is a very rare developmental anomaly which may be associated with intracranial anomalies of the brain. MRI can help in making the diagnosis and also detect the intracranial anomalies in a single study.
Received for publication December 9, 2005.
Revision received February 16, 2006.
Accepted for publication February 22, 2006.
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References
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- Albernaz VS, Castillo M, Hudgins PA, Mukherji SK. Imaging findings in patients with clinical anophthalmos. AJNR Am J Neuroradiol 1997;18:555–61.[Abstract]
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Abstract
Introduction
