A unique case of IgG4 sclerosing dacryocystitis.

IgG4-related ocular adnexal disease, a relatively recently described clinical entity, is important to diagnose because during the acute phase, it responds favorably to corticosteroid treatment. The diagnosis can be confirmed by simple blood tests and histology. IgG4-related dacryoadenitis and generalized orbital disease have been reported; however, this is the first report of IgG4-related disease of the lacrimal sac. We describe an 80-year-old female who presented with a painless erythematous indurated swelling in the right lacrimal sac area with complete obstruction of the right nasolacrimal system. A 9-mm lacrimal sac mass was noted on CT dacryocystogram. Blood tests revealed an elevated serum IgG4 level, and the lacrimal sac histology was characteristic of IgG4-related disease. Corticosteroid treatment was declined by the patient. She was kept under close observation for signs of progression, systemic involvement, and potential malignant transformation.