IgG4-related fibrosing mediastinitis: clinical presentation, treatment efficacy and comparison with IgG4-RD without fibrosing mediastinitis

Objective This study aimed to investigate the clinical characteristics and treatment efficacy of immunoglobulin G4 (IgG4)-related fibrosing mediastinitis (IgG4-RFM) and to compare IgG4-RFM patients with IgG4-related disease (IgG4-RD) patients without fibrosing mediastinitis (FM). Methods Twenty IgG4-RFM patients and 60 randomly matched IgG4-RD patients without FM from a prospective cohort at the Peking Union Medical College Hospital (PUMCH) were enrolled from 2011 to 2019. Patient demographic data, clinical characteristics, laboratory parameters and treatment efficacy were analysed. Results The prevalence of IgG4-RFM in our cohort was 2.8%. The average age was 51.7 +/- 14.8 years, and the patients were predominantly male (60.0%). Periaortic masses (75.0%) and paravertebral masses (35.0%) were the most common characteristic imaging findings of IgG4-RFM. Compared with male patients with IgG4-RFM, a lower percentage of female patients had abdominal aorta involvement (p=0.015). IgG4-RFM patients had a shorter disease duration; lower percentage of allergy history, submandibular gland involvement, and pancreas involvement; lower serum IgG4; higher erythrocyte sedimentation rate (ESR) and high-sensitivity C-reactive protein (hsCRP) levels; and a higher percentage of single organ involvement than patients without FM (p<0.001, p=0.008, p=0.033, p=0.001, p=0.027, p=0.007, p=0.004 and p=0.047, respectively). After treatment, 94.7% of patients achieved a mediastinal soft tissue reduction of >30%. Conclusion IgG4-RFM is a distinct fibrotic subtype of IgG4-RD. Periaortic masses and paravertebral masses were the most common characteristic imaging findings of IgG4-RFM. Most IgG4-RFM patients respond well to glucocorticoid (GC) and inununosuppressant treatments.