Background/Purpose: ACR/EULAR Classification criteria for IgG4-related disease (IgG4-RD) newly published [1]. On the other hand, four distinctive phenotypes of IgG4-RD have been described [2]. We aimed to identify clinical phenotypes of IgG4-RD and the evaluate usefulness of 2019 ACR/EULAR classification criteria (AECC) for clinical phenotypes in our cohort.

Methods: In the prospective database of the Hacettepe University Vasculitis Research Centre (HUVAC) 92 IgG4-RD patients meeting the 2011 comprehensive diagnostic criteria for IgG4-RD were registered by the end of the May 2021. We reviewed the medical records and determined the following clinical factors: Age, gender, serum levels of IgG4, presence of ANCA or other specific autoantibodies, histopathologies with immunostaining (if available) and distributions of organ involvement. An AECC score was calculated for all cohort.

Results: We included 92 patients (M/F:47/45) with IgG4-RD. 61% of the patients had multiorgan involvement, median (IQR) organ involvement was 2 (1-3) and median (IQR) IgG4 level was 179 mg/dL (89-368). Majority of the patients had retroperitoneal fibrosis/periaortitis (Table). Retroperitoneal and aorta (RPF-Aortitis) accounted for 40% of the phenotypes, followed by head and neck (24%), Mikulicz and systemic (16%), and pancreato-hepato-biliary (PHB) (11%). Nine per cent had an undefined phenotype. Head and neck group had female predominance whereas RPF/aortitis group had male predominance. Mikulicz and systemic group had the highest IgG4 levels.

All of the patients fulfilled the entry criteria for AECC for IgG4-RD. Of the 42 false-negative cases, 7 met one exclusion criteria whereas 35 did not achieve sufficient inclusion criteria scores. 49 (53%) patients got a score ≥20 points, with a mean score of 29.3 points (SD.7.3). MS, PHB and RPF/Aortitis phenotypes met 2019 AECC at a higher rate, although the differences were not statistically significant.

Conclusion: Phenotype results of our cohort are concordant with Asian and American cohorts. RPF-Aortitis phenotype was more prevalent, while PHB and MS were less frequent. The 2019 AECC was met over half of the patients.

Table. Clinical Phenotypes of IgG4-related disease

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/usefulness-of-2019-acr-eular-classification-criteria-aecc-for-igg4-related-disease-differs-between-clinical-phenotypes-of-igg4-rd/