IgG4-related orbital inflammation presenting as unilateral pseudotumor.

IgG4 related systemic disease (IgG4-RSD) has been recognised in the last few years. Orbital pseudotumor as a presentation of IgG4-RSD is one of the rare complaints encountered in pediatric population. It is an inflammatory condition of unknown etiology characterized by tumorous swelling of the organs, characteristic histopathologic changes and elevated IgG4: IgG plasma cells ratio.