Abstract
A girl in the first decade of life presented with a 1.5 year history of gradually progressive bilateral upper eyelid swelling with bilateral proptosis, more prominent on the right side. She had a partial response to oral prednisolone, but symptoms recurred during tapering. Examination showed firm bilateral upper eyelid masses, preserved vision and mild restriction of upward gaze in the right eye. MRI demonstrated right preseptal/periorbital soft tissue thickening. Further evaluation excluded infection, vasculitis, sarcoidosis and malignancy; serum IgG4 level was normal. Biopsy of the right eyelid lesion showed concentric perivascular fibrosis with eosinophil-rich lymphoplasmacytic infiltrate, consistent with eosinophilic angiocentric fibrosis, supporting a diagnosis of possible organ-limited IgG4-related disease. The patient was treated with oral prednisolone and mycophenolate mofetil, resulting in sustained clinical improvement. This case highlights that paediatric IgG4-related disease may present as isolated orbital swelling with normal serum IgG4, making histopathology crucial for diagnosis.