IgG4-related disease of the orbit in an infant.

IgG4-related disease is a chronic fibroinflammatory disorder that is becoming increasingly recognized in the pediatric population. The orbit is one of the most commonly affected sites. We present the youngest case of IgG4-related ophthalmic disease in the literature, with an immunodeficiency phenotype associated with a homozygous IRAK-4 variant gene. We also review the clinical and histological features in children with IgG4-related ophthalmic disease. In addition to the young age of presentation, the case is unique for absence of lacrimal gland involvement, dural enhancement on magnetic resonance imaging, and an association with an IRAK-4 deficiency phenotype. Management required a multidisciplinary approach, with judicious use of immunosuppression. IgG4-related ophthalmic disease should be considered as a differential diagnosis in infants and children presenting with an orbital mass. Further, a particularly young age of onset may indicate an overarching immune dysregulation syndrome.