Purpose

A 44 year old female presented with a three week history of reduced vision in the right eye. She reported a four year history of right exotropia and one year history of right periorbital pain and diplopia. Prior ENT assessment for nasal congestion and hyposmia demonstrated absent nasal septum secondary to prior cocaine abuse. Past medical history included seronegative inflammatory arthritis maintained on 10mg oral prednisolone. The patient reported cocaine abstinence.

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Methods

Visual acuity was LogMAR CF OD 0.3 OS. Examination demonstrated a large angle, right exotropia with hypertropia, dilated pupil, 1mm proptosis and globally restricted right ocular motility. Posterior subcapsular cataract were present OU, with nasal swelling of the right optic disc. Colour vision was not testable due to poor acuity. Orbital MRI demonstrated inflammatory destruction of the nasal septum and lamina papyracea with extension into the right orbital apex, compressing the optic nerve and medial rectus atrophy. Blood tests demonstrated raised CRP, positive MPO antibodies, atypical p-ANCA, and negative PR3 antibodies. Differential diagnoses included GPA and cocaine-induced orbitopathy. Oral prednisolone 40mg was commenced, resulting in improvement in vision to LogMAR 0.3 and reduction in inflammatory markers over three months.

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Results

This case demonstrates the diagnostic dilemma between cocaine-induced orbitopathy and GPA, since the former can mimic the latter. Serology, urine toxicology and biopsy may aid differentiation; however, serology was inconclusive, patient declined toxicology and biopsy was considered too high-risk due to location and potential vision loss.

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Conclusion

Given the diagnostic uncertainty empirical treatment was commenced with immunosuppression alongside Rheumatology. Although immunosuppression is typically associated with GPA, and cocaine abstinence the cornerstone for substance users, there is increasing evidence immunosuppression has a role in cocaine-induced orbitopathy. Early multi-disciplinary involvement is imperative in sight-threatening cases with diagnostic uncertainty.

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Additional Authors

First name	Last name	Base Hospital / Institution
Michelle	Ting	Royal Free Hospital

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