Immunoglobulin G4-related disease (IgG4-rd) is characterized by lymphoplasmacytic infiltration and tissue fibrosis. Orbital manifestations of IgG4-rd may include unilateral or bilateral proptosis, cicatricial extraocular muscle myopathy, orbital inflammation and pain which may mimic ophthalmic Graves’ disease.
A 25-year-old woman has been referred to the endocrinology clinic, 4 months after delivery, with suspected Graves’ orbitopathy. She has had bronchial asthma and recurrent skin rashes of unknown aetiology for the last 10 years and was treated for dacryoadenitis with steroid containing eye drops 5 years ago. During pregnancy she developed eyelid swelling. After delivery, eyelid redness and retrobulbar pain evolved. Proptosis was demonstrated by Hertel’s exophthalmometry. Orbital magnetic resonance imaging showed enlarged lateral and superior rectus muscles in both orbits. Thyroid function tests were in the normal range and no thyroid stimulating hormone (TSH) receptor autoantibodies were present. The eye muscle involvement pattern raised suspicion, and the high IgG4 level with positive histology of the lacrimal gland confirmed the diagnosis of immunoglobulin G4-related orbitopathy. Rapid improvement was observed following oral methylprednisolone.
IgG4-related orbitopathy may mimic Graves’ orbitopathy. Euthyroid patients with no TSH receptor autoantibodies should be evaluated for immunoglobulin G4-related orbitopathy. Once IgG4-related orbitopathy is proven, other manifestations of IgG4-related disease have to be searched for; lifelong follow-up is warranted.