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. The disease is also characterized by involvement of varied organ systems. The authors describe a seven-year-old boy with orbital pseudotumor after two years of initial onset with waxing and waning course, steroid responsive lesion and biopsy suggestive of IgG4-RSD involving the extraocular soft tissue. Treatment with oral corticosteroids and Azathioprine produced a significant decline in the pseudotumor size. It is important for pediatricians to be aware of this condition as appropriate recognition and management is important to prevent long-term damage of the tissue involved. This is the first case of IgG4 related orbital pseudotumor reported from India.