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).