Isolated orbital involvement of IgG4-related disease mimicking malignancy

8th Congress of European ORL-HNS — CEORL-HNS 2026, Gothenburg, İsveç, 25 - 29 Nisan 2026, ss.533, (Özet Bildiri)

K. Önder1

, S. Mete1

, A. Çetin1

, B. Pehlivanoğlu2

1Dokuz Eylül University, Faculty of Medicine, Department of Otorhinolaryngology – Head and Neck

Surgery, Izmir, Turkey, 2Dokuz Eylül University, Faculty of Medicine, Department of Pathology, Izmir,

Turkey

Background & Aim: IgG4-related disease (IgG4-RD) is a chronic fibro-inflammatory disorder that can

affect multiple organs, often simulating malignancy or infection. Orbital involvement represents a

distinct subtype known as IgG4-related ophthalmic disease (IgG4-ROD). Because serum IgG4 levels

may remain normal in up to 40% of patients, tissue biopsy remains the cornerstone for diagnosis. We

report a rare case of isolated orbital IgG4-RD presenting as an orbital apex mass to emphasize the

diagnostic challenges and the importance of early tissue confirmation.

Case Study: A 76-year-old woman presented with progressive right orbital pain and vision loss lasting

four months. Imaging revealed a well-defined soft-tissue mass at the orbital apex extending to the

sphenoid sinus and pterygopalatine fossa, initially suggesting malignancy. Serum IgG4 level was

normal (95 mg/dL). Endoscopic biopsy demonstrated dense lymphoplasmacytic infiltration with

storiform fibrosis and >50 IgG4-positive plasma cells per high-power field (IgG4/IgG ratio 45%),

confirming IgG4-ROD.

Results: Systemic corticosteroid therapy followed by azathioprine produced marked radiologic

regression and resolution of the orbital mass. Nevertheless, visual recovery did not occur because of

irreversible optic-nerve damage caused by diagnostic delay.

Conclusions: Isolated orbital IgG4-RD may closely mimic orbital malignancies. Normal serum IgG4

values do not exclude the diagnosis. Early biopsy and prompt immunosuppressive therapy are

essential to prevent permanent vision loss. Multidisciplinary evaluation by otolaryngology,

ophthalmology, and pathology teams is crucial for optimal outcomes.