Case Report
Congenital Orbital Teratoma: A case report with fetal presentation
https://doi.org/10.21203/rs.3.rs-1553431/v1
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Congenital orbital teratomas are rare entities with few case reports detailing their prenatal and perinatal imaging features. We present the case of a congenital orbital teratoma initially detected as cystic lesion on prenatal ultrasound, with fetal and postnatal imaging showing evolution of characteristic MRI appearances. Knowledge of these appearances and the ability to diagnose these rare entities in fetal life can aid management and operative planning in the immediate postnatal period.
Congential Orbital teratoma
Fetal MRI
Teratomas are congenital tumours derived from the three germ layers. Although rare, the orbit is a recognised location for congenital teratoma1.
We present a case of a congenital orbital teratoma, initially discovered as an incidental cystic lesion in the right orbit during antenatal ultrasound scan.
A fetal MRI performed at 27 weeks of gestation demonstrated a large, thin-walled and well-defined cystic lesion within the right orbit, causing significant proptosis of the globe, stretching of the extraocular muscles and optic nerve, expansion and remodelling of the bony orbit (Figs A-C). At this time point there were no visible septations, solid components, fat or blood products demonstrated. The intracranial and the left orbital structures were normal.
A follow-up fetal MRI study was performed at 36 weeks of gestational age. This demonstrates significant structural changes of the cystic lesion in the right orbit, with reduction in the degree of proptosis, interval development of septations, and multiple small solid components posterior to the globe (Figs D and E).
Post-processed 3D super-resolution reconstructed (SRR) images were performed for both Fetal MRI scans which provided further information regarding the transformation of the cyst between the 9 weeks interval, especially providing a clear overview of the volume of the lesion in relation to the whole head. This was particularly useful information during multidisciplinary meetings for delivery plan and also for parental counselling.
The baby was subsequently delivered via caesarean section at 38 weeks, with multidisciplinary assistance at birth, including obstetric, anaesthetic and ophthalmology support to ensure maximal preservation of the affected eye (Figure F). On day 2 of life approximately 7mls of straw-coloured fluid was sampled. At day 8 of life a contrast-enhanced MRI head was performed with dedicated orbital sequences. This demonstrates a further reduction in the degree of proptosis and an increase in solid components, which showed contrast enhancement following gadolinium administration. Furthermore, T1-weighted fat saturated images show regions of signal dropout within the orbital lesion consistent with macroscopic fat (Figs G-J). The lesion was confined to the orbit with no evidence of any intracranial extension.
At day 9 of life exenteration was performed, with removal of the globe and excision of the orbital lesion as a single specimen. The orbital cavity was markedly expanded and distorted, with bony remodelling and widening of the optic canal.
Pathology examination (Figure K) revealed a firm grey tumour measuring approximately 3.5 cm in diameter, containing cystic and solid elements. The histology confirmed presence of mature tissue representing embryonic layers ectoderm, mesoderm and endoderm. These included patches of mature neuroglial tissue, mesenchymal tissue comprising adipose and cartilage tissue, skin adnexal structures and intestinal-type tissue. There were no immature elements or features of malignancy noted. The overall features are consistent with that of a mature (benign) cystic teratoma. The exenterated right eye showed no significant pathology.
There were no immediate perioperative complications and the patient went on to have oculoplastic reconstruction which is currently ongoing (Figure I).
Teratomas are congenital germ cell tumours composed of all three germ cell layers (endoderm, ectoderm, mesoderm). Histopathological classification characterise as either mature teratoma, composed of fully differentiated cell types, or immature teratoma, containing undifferentiated tissues. Whereas mature teratomas generally behave as a benign tumour after complete resection, immature teratomas follow a more aggressive course with a greater propensity for recurrence2.
This case posed a diagnostic challenge due to the findings of a large, thin-walled and well-defined cystic orbital mass on initial MRI imaging, with no suggestion of solid, fatty or haemorrhagic components at 27 weeks of gestation. The differential for these appearances is wide and include congenital orbital cysts, venolymphatic malformations, and rare entities such as optic nerve sheath meningoceoeles 3. The rapid metamorphosis from an orbital cystic lesion in fetal life, to the development of solid and enhancing components postnatally, has recently been reported separately 4, and this finding may reflect the natural history of orbital teratomas. This case demonstrates this transformation in utero, highlighting the importance of in-utero MR imaging follow-up in the presence of undefined orbital cystic lesion, to improve diagnostic accuracy, to assist on parental counselling and to guide for birth planning. Furthermore, this case highlights the importance of utilising dedicated post-natal MR orbital protocol, including the use of pre- and post-contrast T1-weighted images, both with and without fat saturation, to allow detection of macroscopic fat, a key feature of germ cell tumours.
This is a retrospective case report and ethical approval was not required. Parental consent was obtained for article submission and for permission to use the provided photographs.
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Authors' contributions: All the authors have made substantive contributions to the article and assume full responsibility for its content
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No competing interests reported.
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31 May, 2022
Reviewers agreed at journal
21 May, 2022
Reviewers invited by journal
14 May, 2022
Editor assigned by journal
14 May, 2022
Submission checks completed at journal
09 May, 2022
First submitted to journal
13 Apr, 2022
You are reading this latest preprint version