AB0853 IGG4-RELATED DISEASE CAUSING OCULAR NERVE PALSIES AND ORBITAL APEX SYNDROME: CASE REPORT AND LITERATURE REVIEW

Background:IgG4-Related Disease (IgG4-RD) is a systemic immune-mediated fibroinflammatory condition. The epidemiology is not well defined: it usually affects adults from middle-age onwards, predominantly male. Both B and T-cells are central in IgG4-RD pathogenesis, as demonstrated by the efficacy of B-cell depletion therapy.IgG4-RD can affect multiple organs including the central and peripheral nervous system, producing a constellation of clinical symptoms and signs, depending on the organ structures involved.IgG4-related orbital disease is relatively rare can implicate all extra-ocular muscles, structures emerging from the Orbital apex, optic canal, or superior and inferior orbital fissure. Depending on the structures involved, it can produce different or sometimes subtle clinical presentations, posing diagnostic challenge. There were case reports of IgG4-related ophthalmic disease misdiagnosed as intraocular tumour.Objectives:IgG4-RD is increasingly recognised as an entity affecting the head and neck region. However, it rarely involves skull base and presents with orbital apex syndrome. In this current case report, we describe an interesting case of IgG-related orbital disease presenting with ocular nerve palsies and orbital apex syndrome.Methods:Case report.Results:A 36-year-old gentleman with cocaine and alcohol misuse presented with a 2-month history of left sided headache, diplopia, recurrent ear infections, otalgia and hearing loss. Initial imaging suggested left otomastoiditis and intravenous antibiotics were commenced. Contralateral partial third nerve palsy with pupil sparing was elicited. 2 months later, there was worsening right eye ptosis, proptosis, right relative afferent pupillary defect, reduced visual acuity and colour vision as well as a near-complete ophthalmoplegia. Subsequent imaging showed worsening soft tissue swelling centred on the upper left parapharyngeal and masticator space, with multiple perineural enhancement and lateral extension to right orbital apex and orbital fissures. Blood tests only revealed raised IgG4 subclass. Infectious aetiology was excluded. Left nasal mass biopsy performed showed no fungal organism or malignancy. There were lymphoplasmacytic proliferation but no storiform fibrosis or obliterative phlebitis. IgG4 immunostaining on two assessable fields revealed 22 and 17 positive plasma cells respectively, and an IgG4: IgG ratio of <10%, and 50% in the other. Significant improvement was seen clinically and radiologically with antibiotics and a tapering regime of oral Prednisolone. Patient was commenced on Azathioprine as long term immunosuppression.Conclusion:A high degree of clinical suspicion is necessary to diagnose IgG4-RD when presenting with orbital apex syndrome and ocular nerve palsies,IgG4-RD can mimic mastoiditis of infectious aetiology. Other differentials may include cocaine-induced midline destructive lesions and granulomatosis with polyangiitis. The diagnosis can be supported by elevated serum IgG, elevated IgG index and pathognomonic histopathological findings. . The diagnosis of IgG4-related orbital disease should be deliberated on by a multidisciplinary group, with every effort being made to exclude an infectious aetiology, before embarking on immunosuppressive therapy.Primary treatment is with steroids. However, immunotherapy using azathioprine can be utilised in recurrent disease or patients with steroid intolerance.References:[1]Goto H, Ueda S. Immunoglobulin G4-related ophthalmic disease involving the sclera misdiagnosed as intraocular tumor: report of one case. OculOncolPathol. 2016;2(4):285–8.[2]Ohyama K, Koike H, Iijima M, et al. IgG4-related neuropathy: a case report. JAMA Neurol. 2013;70(4):502–5.[3]AbdelRazek MA, Venna N, Stone JH. IgG4-related disease of the central and peripheral nervous systems. Lancet Neurol. 2018;17(2):183–92.[4]Kamekura R, Takahashi H, Ichimiya S. New insights into IgG4-related disease: emerging new CD4+ T-cell subsets. Curr Opin Rheumatol. 2019;31(1):9–15.Disclosure of Interests:None declared