Morphologic Cross-Sectional Imaging Features of IgG4-Related Orbitopathy in Comparison to Ocular Adnexal Lymphoma

Annemarie Klingenstein,1 Aylin Garip-Kuebler,1 Siegfried Priglinger,1 Christoph Hintschich,1 Ullrich G Mueller-Lisse2 1Department of Ophthalmology, Ludwig-Maximilians-University, Munich, Germany; 2Department of Radiology, Ludwig-Maximilians-University, Munich, GermanyCorrespondence: Annemarie KlingensteinLudwig-Maximilians-University, Department of Ophthalmology, Klinikum der Universität München, Campus Innenstadt, Mathildenstraße 8, Munich, D-80336, GermanyTel +49 89 44005 3811Fax +49 89 44005 5160Email Annemarie.Klingenstein@med.uni-muenchen.deAim: To detect radiological features that, in addition to clinical findings, may aid in correct differentiation between IgG4-related ophthalmic disease (IgG4-ROD) and ocular adnexal lymphoma (OAL).Methods: In this retrospective, single-center, comparative analysis, we compared cross-sectional imaging findings of 13 consecutive patients with histologically proven IgG4-ROD and a control group of 29 consecutive OAL-patients diagnosed between 10/2014 and 09/2019. Statistical significance was accepted at a p< 0.05 significance level.Results: IgG4-ROD-patients had longer time-to-diagnosis, higher orbital recurrence rates, but smaller lesions compared to OAL-patients (p=0.002; p=0.006 and p=0.006; Mann–Whitney U-test). Frequent cross-sectional imaging findings in both IgG4-ROD-patients and OAL-patients included extraocular muscle enlargement (92% and 93%, respectively; most often in the lateral rectus muscles and the levator-complex), and lacrimal-gland enlargement (85% and 83%, respectively). Other imaging findings comprised infraorbital nerve-involvement (IgG4-ROD, 23%, OAL, 17%) and orbital fat inflammation (IgG4-ROD, 23%, OAL, 28%). Bony infiltration and remodeling, heterogenous contrast-media distribution, and infiltration of the lacrimal system were seen slightly more often in IgG4-ROD (23%, 38%, 15% and 15% versus 17%, 14%, 3% and 7%). However, cross-sectional imaging features did not differ significantly between patient subgroups. Clinical symptoms predominantly occurred unilaterally (IgG4-ROD, 9/13, 69%, OAL, 24/29, 83%), while imaging findings were most often bilateral (IgG4-ROD, 11/13, 85%, OAL, 23/29, 79%, p< 0.001, McNemar test).Conclusion: No morphological cross-sectional imaging sign could reliably distinguish between IgG4-ROD and OAL, leaving histopathology indispensable for definite diagnosis. Yet, importantly, for both IgG4-ROD and OAL, cross-sectional imaging frequently detected bilateral orbital disease when only one eye was clinically affected.Keywords: IgG4, idiopathic orbital inflammation, CT, ocular adnexal lymphoma