Purpose

Background: Arteriovenous malformation (AVM) of the orbit is a rare subtype of vascular malformation that can pose significant diagnostic challenges with potential vision-threatening complications, especially in the context of prior trauma.

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Methods

Case: We report a patient with prior orbital trauma who presented with unilateral proptosis and intermittent monocular diplopia.

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Results

Magnetic resonance imaging (MRI) showed a lobulated enhancing left ethmoidal soft tissue lesion 2.8×1.6×1.5cm in size, with erosion of the left lamina papyracea and invasion of the left superior oblique, medial rectus and inferior rectus muscles. Endoscopic biopsy was technically demanding and was complicated by brisk hemorrhage upon breaching the tumor capsule. A multidisciplinary tumor board deemed the lesion unsuitable for embolization or gamma knife surgery due to high procedural risks. Diagnosis was eventually confirmed via excisional biopsy through a left anterior orbitotomy. Histopathology showed fibroadipose tissue with irregular thick-walled vessels of varying sizes, consistent with a diagnosis of AVM and no evidence of malignancy. The patient was subsequently managed conservatively with interval surveillance MRI and has remained stable since. Visual outcomes were good with a visual acuity of 6/7.5 and full ocular motility, with resolution of his proptosis.

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Conclusion

Conclusions: Diagnosis of orbital AVM can be challenging with overlapping clinical and radiological features with orbital masses of other aetiologies especially in the context of post-traumatic sequelae. Significant intraoperative bleeding can be an important diagnostic clue. Management should be tailored based on the characteristics of the lesion, with consideration of the procedural risks and the patient’s fitness for invasive procedures.

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Additional Authors

First name	Last name	Base Hospital / Institution
Sze Chuan	Ong	National University Hospital, Singapore
Jianbin	Ding	National University Hospital, Singapore
Blanche	Lim	National University Hospital, Singapore

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