AB0896 Cogan Syndrome: Differential Response To Biologic Agents and Role of PET-CT in The Increased Diagnosis of Aortitis

Background Cogan syndrome (CS) is a rare inflammatory disorder typically characterized by interstitial keratitis and audiovestibular symptoms. Patients may also develop other inflammatory ocular symptoms, progressive sensorineural hearing loss and systemic manifestations including aortitis, aortic insufficiency, and cerebral vascular manifestations. It has been classified as “variable vessel vasculitis”, and autoantibodies against inner ear and endothelial antigens has been claimed in its pathogenesis. There is no diagnostic test, and classification of patients as CS is still problematic due to variability of clinical findings. Glucocorticoids are the mainstay of CS treatment. Also, azathioprine, methotrexate, and biological agents including TNF and IL-6 inhibitors have been tried in the treatment of CS. Objectives We herein report the diagnostic and therapeutic findings of eight patients diagnosed with CS or CS-like illness with an aim of characterisation of the spectrum of CS. Methods We retrospectively reviewed the charts of the eight patients diagnosed with CS or CS-like illness according to their clinical manifestations. All of the clinical findings, laboratory and imaging results and treatment responses were recorded using a standard form. Because of the sample size, no statistical analysis was carried out. Results are summarized as descriptive findings. Results The mean age of the patients diagnosed with CS was 36 years, and the mean follow-up duration was 5.6 years. Demographic and clinical characteristics of CS patients are summarized in Table 1. Sensorineural hearing loss and intraocular findings were present in all patients. We observed variability in ocular findings, which included typical interstitial keratitis in three, scleritis in four patients, and occlusive retinal vasculopathy in one patient. Although aortitis has rarely been reported previously, diagnostic work-up included PET-CT imaging in three patients, and it revealed positive findings compatible with aortitis. One of our patients needed aortic valve replacement due to severe aortic regurgitation. All patients responded well to high dose corticosteroids initially. Partial or complete remission could be achieved in three patients with a mild disease course with azathioprine or methotrexate. Remaining 5 patients required biologic agents to control inflammatory activity. One patient with polyarthritis responded adalimumab and methotrexate combination. However, no response or even exacerbation of findings were observed with anti-TNF agents in two patients. In four patients, a partial, near-complete, or complete remission could be achieved with IL-1 blockade. Conclusions Patients with CS comprise a heterogeneous group, which may include some yet undiagnosed hereditary autoinflammatory conditions. Aortic involvement has rarely been reported in CS patients, but PET-CT imaging may help diagnosing asymptomatic patients with inflammatory imaging findings in aorta. Early and effective treatment may prevent organ damage, and a differential response to IL-1 blocking biologic agents requires further investigation for both understanding its pathogenesis and better management of refractory patients. Disclosure of Interest None declared