To investigate the clinical characteristics of idiopathic orbital inflammatory disease (IOI) with paranasal sinusitis.

This study is a retrospective, comparative case series of patients who were diagnosed with IOI between January 2009 and December 2016. This study included patients with available medical and radiologic data at diagnosis and who participated in follow-up for more than 12 months after treatment. The patients were divided into two groups according to accompaniment of paranasal sinusitis and were compared.

Among 101 patients with IOI, 13 (12.9%) were identified to have paranasal sinusitis. The incidence of pain was higher in patients with sinusitis (69.2%) than in patients without sinusitis (25.0%, p = 0.003). More patients with paranasal sinusitis experienced recurrence after systemic steroid therapy (69.2%) than in the other group (34.1%, p = 0.033). Additional immunosuppressants and/or radiation therapy were needed only in 9.1% patients without sinusitis but in 38.5% patients with sinusitis ( p = 0.039).

IOI patients with sinusitis showed a significantly higher recurrence rate. More careful follow-up of patients during steroid tapering and treatment of sinusitis might be helpful to prevent recurrence of IOI.