Abstract ID: 26-300
Isolated inferior oblique muscle involvement as a novel manifestation of orbital metastasis
Author: Sunwoo Chang Base Hospital / Institution: Faculty of Health and Medical Sciences, Adelaide University, Adelaide, Australia
Presentation Type: ePoster Presentation
Purpose
To report two rare cases of solitary inferior oblique (IO) muscle involvement as an atypical presentation of orbital metastasis.
Methods
A retrospective, observational case series of two patients with isolated IO muscle involvement secondary to systemic malignancy. The first case was a 47-year-old lady with a known metastatic ileal neuroendocrine tumour. The second patient was a 28-year-old lady with recurrent, biopsy-proven sinonasal alveolar rhabdomyosarcoma. Both patients presented with diplopia and hypertropia, with no proptosis.
Results
In the first case, Gallium-68 Dotatate scans showed an enhancing lesion in the right IO, confirming neuroendocrine origin. Orbital magnetic resonance imaging in both cases demonstrated focal, marked IO enlargement with a low apparent diffusion coefficient. In isolated IO metastasis, clinical findings can be subtle, with double vision as the presenting complaint.
Conclusion
The pattern of solitary IO metastasis is rare and has not yet been reported. Recognition of this entity supports a low threshold for orbital MRI or PET/Dotatate scan in patients with known malignancy presenting solely with diplopia, obviating the need for orbital biopsy.
Additional Authors
| First name | Last name | Base Hospital / Institution |
|---|---|---|
| Ayushi | Agarwal | South Australian Institute of Ophthalmology, Royal Adelaide Hospital, Adelaide, Australia |
| Jai | Paris | South Australian Institute of Ophthalmology, Royal Adelaide Hospital, Adelaide, Australia |
| James | Slattery | Flinders Eye Centre Clinic, Flinders Drive, Bedford Park, South Australia |
| Dinesh | Selva | South Australian Institute of Ophthalmology, Royal Adelaide Hospital, Adelaide, Australia |