Background: IgG4-related disease (IgG4-RD) is an immune-mediated condition first recognized as a distinct entity in 2003 [1]. It is a highly heterogeneous disease because it can affect almost any organ. The most common condition are the lacrimal glands, major salivary glands, pancreas and retroperitoneum; followed by the orbit, lung, bile ducts and kidney involvement. Less frequently, it involves the pachymeninges, thyroid gland and aorta. Most of the data on this disease come from Asian countries and the United States. In Spain, there are no registries for IgG4-RD and it is known that sociodemographic characteristics are an important factor in these patients, potentially influencing clinical manifestations, progression, and treatment.

Objectives: The aim of this study was to describe the characteristics of patients diagnosed with IgG4-RD and assessed by the rheumatology department at our center.

Methods: We conducted a retrospective descriptive study of patients diagnosed with IgG4-RD at the Complejo Hospitalario Universitario A Coruña (CHUAC) who were evaluated in the rheumatology department from 2012 to December 2024. The diagnosis was made at the discretion of the physician (clinical diagnosis). Sociodemographic variables, clinical manifestations, laboratory findings, imaging data, pathological anatomy results and treatment information at the time of diagnosis were collected.

Results: A total of 19 patients were diagnosed with ER-IgG4. The majority were men (68.42%), Caucasian (89.47%) with a mean age of 63 years. The most common type of involvement among our patients was retroperitoneal involvement (42.11%), followed by pancreatic involvement (26.32%) and kidney involvement (21.05%) (Table 1). At the time of diagnosis, most patients showed elevated acute-phase reactants (Table 2). Total IgG levels were normal in 8 out of 14 patients and IgG4 levels were normal in 7 out of 14 patients. All patients underwent imaging studies at diagnosis, including 7 ultrasounds, 7 magnetic resonance imaging, 16 computed tomography (CT) and 8 positron emission tomography-CT scans. Biopsies were performed in 18 of the 19 patients, targeting the site with the most significant involvement. Histopathological analysis revealed storiform fibrosis in only 3 of the 18 biopsies and obliterative phlebitis in one. IgG4-positive cells were identified in 16 of the 18 biopsies, with a mean of 37.54 cells. Additionally, the IgG/IgG4 ratio showed a mean of 48.8%. A pathological result is defined as more than 10 IgG4-positive cells per high-power field and an IgG/IgG4 ratio greater than 40% [3, 4]. Five patients received high-dose corticosteroid therapy, with 3 of them receiving 250 mg of methylprednisolone boluses. Oral corticosteroids were initiated in 17 of the 19 patients, with an average starting dose of 53.75 mg/day. Of these, 10 patients remain on corticosteroids. Additional treatments are detailed in Table 2. Currently, only one patient continues with Azathioprine, two discontinued it due to hepatotoxicity and another two due to gastrointestinal toxicity. Four patients are still receiving Methotrexate, and three are on Rituximab therapy. The mean follow-up time for these patients was 51.18 months. There were two deceased patients, with causes of death unrelated to IgG4-RD. As limitations, this study is retrospective and not all patients had complete laboratory parameters available at the time of diagnosis.

Conclusion: The most frequent clinical manifestations observed in patients evaluated at the rheumatology department of our center were retroperitoneal and pancreatic involvement. Two patients presented with cerebral vasculitis, an uncommon manifestation. Notably, no cases of lacrimal gland involvement, a commonly reported manifestation, were recorded. IgG4 levels were within the normal range in 36.8% of the patients diagnosed with IgG4-RD.

REFERENCES: [1] Kamisawa T. IgG4-Positive Plasma Cells Specifically Infiltrate Various Organs in Autoimmune Pancreatitis. Pancreas. 2004;29(2):167.

[2] Perugino CA, Stone JH. IgG4-related disease: an update on pathophysiology and implications for clinical care. Nat Rev Rheumatol. 2020;16(12):702-14.

[3] Wallace ZS, Naden RP, Chari S, Choi H, Della-Torre E, Dicaire JF, et al. The 2019 American College of Rheumatology/European League Against Rheumatism Classification Criteria for IgG4-Related Disease. Arthritis Rheumatol Hoboken NJ. 2020;72(1):7-19.

[4] Umehara H, Okazaki K, Masaki Y, Kawano M, Yamamoto M, Saeki T, et al. Comprehensive diagnostic criteria for IgG4-related disease (IgG4-RD), 2011. Mod Rheumatol. 2012;22(1):21-30.

Acknowledgements: NIL.

Disclosure of Interests: None declared.

© The Authors 2025. This abstract is an open access article published in Annals of Rheumatic Diseases under the CC BY-NC-ND license ( http://creativecommons.org/licenses/by-nc-nd/4.0/ ). Neither EULAR nor the publisher make any representation as to the accuracy of the content. The authors are solely responsible for the content in their abstract including accuracy of the facts, statements, results, conclusion, citing resources etc.