Abstract ID: 26-428
Orbital Inflammation Revisited: When the Diagnosis Changes
Author: Leena Koshak Base Hospital / Institution: King Fahad Armed Forces Hospital
Presentation Type: ePoster Presentation
Purpose
To report a rare case of bilateral conjunctival reactive lymphoid follicular hyperplasia with IgG4-positive plasma cell infiltration in an adolescent patient, emphasizing the diagnostic challenges in differentiating it from lymphoma and IgG4-related ophthalmic disease (IgG4-ROD).
Methods
A 16-year-old previously healthy male presented with progressive bilateral conjunctival redness and subconjunctival vascularized masses for 10 months. Ophthalmic examination, orbital imaging, autoimmune and infectious screening, excisional biopsy, histopathology, and flow cytometry were performed. Multidisciplinary evaluation by ophthalmology, hematology, rheumatology, and lymphoma board teams was undertaken. The patient was treated with rituximab and monitored clinically.
Results
Examination revealed bilateral salmon-pink vascularized subconjunctival lesions with feeder vessels. MRI demonstrated no orbital mass or extraocular muscle involvement. Histopathology showed reactive lymphoid follicular hyperplasia with increased IgG4-positive plasma cells (>30/HPF) in one specimen, while flow cytometry excluded lymphoma by demonstrating no light-chain restriction. Despite IgG4-positive infiltration, established diagnostic criteria for IgG4-RD and IgG4-ROD were not fulfilled due to lack of characteristic imaging findings, low IgG4/IgG ratio, and absence of systemic involvement. The patient received rituximab induction therapy (375 mg/m² weekly ×4) with clinical improvement, lesion flattening, and no major adverse effects
Conclusion
IgG4-positive plasma cell infiltration is not specific for IgG4-RD and may occur in reactive inflammatory conditions. This case highlights the importance of comprehensive clinicopathologic correlation before assigning a diagnosis of IgG4-RD. In pediatric patients, bilateral conjunctival lymphoid lesions require exclusion of lymphoma through biopsy and flow cytometry.
Conclusions
Reactive lymphoid hyperplasia with IgG4-positive plasma cells represents a diagnostic gray zone that may mimic lymphoma and IgG4-RD. Multidisciplinary assessment and long-term surveillance are essential, while rituximab may serve as a steroid-sparing therapeutic option in selected cases.