IgG4-Related Disease: Fibrofire to B-Cell Breakthroughs

IgG4-related disease (IgG4-RD) is a systemic immune-mediated disorder that may involve multiple organs and typically presents with inflammatory tissue enlargement and variable fibrotic changes. Since its recognition in the early 2000s, IgG4-RD has been increasingly recognized as a systemic condition encompassing a wide range of clinical manifestations. The latter often mimicking malignancy, infection or other autoimmune diseases contribute to persistent underdiagnosis and delayed treatment. Yet, early recognition is crucial, as timely immunosuppressive therapy can induce remission and prevent irreversible fibrotic sequelae. This narrative review synthesizes current knowledge on the epidemiology, immunopathogenesis, clinical spectrum, diagnostic criteria, differential diagnoses and therapeutic strategies of IgG4-RD, with particular emphasis on evolving targeted therapies that are reshaping disease management and prognosis