IgG4-related disease (IgG4-RD) is a recently recognized fibro-inflammatory disorder involving virtually any organ system [1,2]. Clinical-pathological hallmarks of IgG4-RD include mass-forming lesions, elevated serum IgG4 levels in the majority of patients, and a highly conserved histopathology of the affected organs [1,3]. IgG4-RD promptly responds to glucocorticoids (GC) therapy but relapses are observed in up to 50% of patients within three years, not only after corticosteroids withdrawal but also during tapering [4,5].
