AB1409 IgG4-RELATED DISEASE IN WESTERN SAUDI ARABIA: A CASE SERIES

Background: IgG4-related disease (IgG4-RD) is a multisystem autoimmune condition that was first recognized in this century. It is characterized by lymphoplasmacytic inflammation and fibrosis in the involved tissues including, but not limited to, the pancreas, hepatobiliary tract, salivary gland, orbits, and lymph nodes. IgG4-RD is diagnosed by demonstration of tumefactive infiltration of IgG4 positive plasma cell in histopathological biopsies of affected tissues in addition to elevated serum IgG4 levels. The current guidelines for IgG4-RD include that a serum level of ≥ 1.35 g/L is the threshold for making a definite diagnosis [1]. However, this has been widely contested, as many of biopsy confirmed cases of IgG4-RD were reported with levels below 1.35 g/L [2-3]. The disease is reportedly more common in males aged between 50 and 70, responds positively to glucocorticoids, and may require disease-modifying anti-rheumatic drugs (DMARDs) for maintenance. Objectives: In this study we aimed to analyze the epidemiological features, clinical presentation, and treatments of IgG4-RD of all biopsy-confirmed cases at a tertiary center in western Saudi Arabia to assess the disease courses and outcomes in our population. Methods: A retrospective chart review of patients diagnosed with IgG4-RD between January 2011 and January 2023 at King Abdulaziz Medical City, Jeddah, a tertiary care center in Western region of Saudi Arabia. All participants have signed informed consent for their anonymized medical records to be used for research purposes. Included cases were all adults aged 14 or older with biopsy proven conditions within the study period. All data analyses were performed using the Statistical Packages for Software Sciences (SPSS) version 26. Results: A total of ten patients have met the inclusion criteria. The mean age was 46.9 (SD 16.5), with 60% being females. Mean BMI of the patients was 30.9 (SD 5.44) kg/m2. The most common presenting complaint was abdominal pain (60%). The mean value of IgG4 was 1.48 (SD 1.31), while the mean time to diagnosis duration was 15.7 (SD 21.2) months. The most used maintenance regimen was Prednisolone along with Mycophenolate mofetil (MMF) in four out of the ten cases. The overall outcome revealed that 80% of the patients were asymptomatic on maintenance therapy. Additionally, the most associated comorbidity was hypothyroidism (40%), followed by diabetes mellitus (30%) and heart disease (20%). Table 1 shows the characteristics of the included patients. Conclusion: In contrast to most previous reports, sixty percent of identified patients were female, and half of the overall sample were below the age of 50. Although the overall enrolled number in our analysis is relatively small, these variations in demographics trends are not insignificant as they may suggest a tendency for younger age of presentation of IgG4-RD with female predominance in our local population. Additionally, within our cohort, half of the patients had a serum level of IgG4 below the threshold set by the guidelines. These findings while at odds with the guidelines do not seem to be outliers and suggest that serum level thresholds of IgG4 may be non-specific and need to be revisited in future updates to the diagnostic criteria. Lastly, there was an overwhelming positive response to glucocorticoid and DMARDs therapy which is in line with known IgG4-RD characteristics. REFERENCES: [1] The 2020 revised comprehensive diagnostic (RCD) criteria for IgG4-RD. DOI: 10.1080/14397595.2020.1859710. [2] IgG4-Related Disease: clinical and Laboratory Features in One Hundred Twenty-Five Patients. DOI:10.1002/art.39205. [3] Multicentric Castleman's disease with abundant IgG4-positive cells: a clinical and pathological analysis of six cases. DOI:10.1136/jcp.2010.082958. Table 1. Patients characteristics (n=10) Acknowledgements: NIL. Disclosure of Interests: None declared.