IgG4-related Fibrosing Mediastinitis: Clinical Presentation, Treatment Efficacy and Comparison with IgG4-RD Without Fibrosing Mediastinitis.

OBJECTIVES: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%. CONCLUSIONS: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 immunosuppressant treatments.