Idiopathic (non-specific) orbital inflammation

Orbital inflammatory disease is a broad spectrum of orbital diseases comprising of infections and inflammations which may pose potential threat to life and/or vision. It is difficult for the clinician to diagnose these conditions based on clinical examination alone. Imaging features may overlap posing further diagnostic dilemma. Idiopathic orbital inflammation, also known as non-specific orbital inflammation, is one of the commonest diseases encountered in oculoplastic practice characterized by an inflammatory process involving 1 or more orbital tissue without any associated local or systemic cause. IOI is a diagnosis of exclusion and a variety of mimics need to be excluded to facilitate timely and appropriate management of patients with IOI. We comprehensively review the clinico-radiologic and histopathologic features of IOI with an emphasis on its differential diagnosis.