Clinical and Prognostic Significance of Serum IgG4 in Chronic Periaortitis. An Analysis of 113 Patients

Abstract

Objective: Chronic periaortitis (CP) is a rare fibro-inflammatory disorder that incorporates idiopathic retroperitoneal fibrosis, inflammatory abdominal aortic aneurysms, and perianeurysmal retroperitoneal fibrosis. CP is included in the spectrum of IgG4-related disease. Since CP patients rarely undergo diagnostic biopsies, serum IgG4 levels are often used to classify CP as IgG4-related. However, the clinical and prognostic significance of serum IgG4 in CP is unknown. Methods: We measured serum IgG4 in active CP patients and compared the clinical characteristics, response to therapy and outcome of patients with high and normal levels. We also tested the diagnostic significance of IgG4 by comparing its levels in CP patients, healthy and disease controls (malignancies, Erdheim-Chester disease, large-, and small-vessel vasculitis). Results: We studied 113 consecutive patients with active CP. Twenty-four (21.2%) had high serum IgG4 (>135 mg/dL). The demographic, laboratory, and clinical characteristics of patients with high and normal IgG4 were similar, and so were the rates of ureteral obstruction and the disease characteristics on CT, MRI, and 18 F-FDG-PET. Patients with high IgG4 only had a higher frequency of extra-retroperitoneal fibro-inflammatory lesions ( p = 0.005). There were no significant differences in response to therapy and relapses between the two groups. Serum IgG4 levels did not discriminate CP from controls. Conclusions: Serum IgG4 levels are high in a minority of CP patients and do not identify specific clinical or prognostic subgroups; only a higher frequency of extra-retroperitoneal lesions is found in high-IgG4 patients. Serum IgG4 levels do not help in the differential diagnosis between CP and its mimics.

Renal Involvement in Retroperitoneal Fibrosis: Prevalence, Impact and Management Challenges

“… 8 Therefore, serum IgG4 levels are of limited value in differentiating IgG4-related RPF from non-IgG4-related IRPF and other inflammatory or neoplastic disorders. On the other hand, because IRPF patients with high serum IgG4 levels more frequently have extra-retroperitoneal fibro-inflammatory lesions, 35 an appropriate systemic screening for other potentially involved sites should be performed in such patients.…”

“…In comparison with non-IgG4-related IRPF, some studies showed a higher recurrence rate in IgG4-related RPF, 4 while others demonstrated no significant differences in the response to therapy or relapses between the two group. 35 On the other hand, several studies investigated relapse predictors of IgG4-RD not limited to IgG4-related RPF. In type 1 autoimmune pancreatitis (AIP), the pancreatic lesion of IgG4-RD, the risk factors for relapse were reported to include absence of low-dose maintenance glucocorticoid treatment, presence of IgG4-related sclerosing cholangitis, and high immune complex level in long-term observational studies or randomized controlled trials.…”

Rituximab for chronic periaortitis without evidence of IgG4-related disease: a long-term follow-up study of 20 patients

“…However, some patients are refractory, frequently relapsing or have contraindications to glucocorticoids. The anti-CD20 monoclonal antibody rituximab proved efficacious in systemic forms of IgG4-related disease (IgG4-RD) including IgG4-related CP,3 but data on IgG4-unrelated CP are scarce 4–6. In this study, we tested rituximab in CP patients without evidence of IgG4-RD who had relapsing/refractory disease or contraindications to standard-dose glucocorticoids.…”

Clinical characteristics of IgG4-related retroperitoneal fibrosis versus idiopathic retroperitoneal fibrosis

“…It was found that IRPF patients got a diagnosis at an earlier age than IgG4-related RPF patients, although the comparison between the two groups fell short of statistical significance. In 2019, Maritati et al [ 23 ] conducted a retrospective observational study including 113 chronic periaortitis (CP) patients, which comprised IRF, IgG4-RPF, and inflammatory abdominal aortic aneurysms patients. They also found an earlier age at diagnosis in CP patients with normal serum IgG4 level.…”