AB1016 Rituximab Treatment in Patients with Idiopathic Sclerosing Orbital Inflammation

Background Idiopathic sclerosing orbital inflammation (ISOI) is a rare disease characterized by fibrous pseudotumor formation, inflammatory changes and poor response to corticosteroids, immunosupressive therapy or radiotherapy. Objectives In this report, 2 patients with ISOI who were refractory to conventional immunosupressive therapy and were treated with rituximab are presented. Methods Case 1: Ten-year-old girl presented with proptosis, ocular motility restriction, lagophthalmus and optic neuropathy in the right eye. Orbita MRI showed a diffuse, infiltrative mass in the superior and retrobulbar orbit. After tumor debulking and histological examination, the diagnosis of ISOI was made. The treatments with prednisolone, cyclophosphamide, methotrexate and/or azothiopurin failed in achieving a complete remission. After the treatment with rituximab (375 mg/m 2 x4), all inflammatory signs disaapeared dramatically and did not reccur during follow up. Case 2: A 36-year-old female presented with painful proptosis, restrictive myopathy and blepharoptosis in her right eye. Orbita MRI showed an infiltrative mass in the upper orbit, encasing the superior rectus muscle and lacrimal gland. Biopsy showed dense fibrous tissue with a mixed cellular infiltrate consistent with ISOI. Systemic evaluation did not find any accompanying abnormality. The disease initially responded well to the oral prednisolon andmethotrexate treatment, but then recurred with a mass regrowth associated with inflammatory symptoms and optic neuropathy. After a tumor debulking surgery, the patient received rituximab (375 mg/m 2 x4) was commenced. Clinical symptoms completely regressed after this treatment and did not recur during follow up. Results In both patients, following the treatment with rituximab (375 mg/m 2 , 4 cure) the lesions have regressed apparently. Recurrence has not been observed for 6 months. Conclusions Idiopathic sclerosing orbital inflammation is characterized by aggressive, chronic, insidious sclerosis and poor response to corticosteroids and immunosuppressive drugs. The presented 2 cases support that rituximab alone may provide a complete clinical remission in patients refractory to the conventional immunosuppressive drugs. References Galvez-Ruiz A, Chaudhry I, Al Katan H. Idiopathic sclerosing orbital inflammation: presentation of an unusual case with isolated bilateral optic nerve involvement. J Neuroophthalmol. 2013;33:308-10. Li Y, Lip G, Chong V, Yuan J, Ding Z. Idiopathic orbital inflammation syndrome with retro-orbital involvement: a retrospective study of eight patients. PLoS One. 2013;8:e57126. Pemberton JD, Fay A.Idiopathic sclerosing orbital inflammation: a review of demographics, clinical presentation, imaging, pathology, treatment, and outcome. Ophthal Plast Reconstr Surg. 2012;28:79-83. Disclosure of Interest None declared