Enfermedad sistémica relacionada con inmunoglobulina G4: ¿por qué interesa al reumatólogo?

Immunoglobulin G₄-related systemic disease is a recently defined emerging disorder characterized by a diffuse mass-forming inflammatory reaction. The mass can be solitary or multiple. This entity affects the exocrine glands, lymph nodes and extranodal tissue, with a lymphoplasmacytic infiltrate rich in IgG₄-positive cells, fibrosclerosis and obliterative phlebitis affecting medium and small caliber veins. Elevation of serum IgG₄ is often present, but not always. The clinical features are highly variable, as this entity can affect single or multiple organs, with a synchronous or metachronous pattern. Two of the most frequent characteristics are the presence of a mass or localized inflammation, and a past history of allergic disease. Diagnosis requires integration of clinical, serological, imaging, histopathological and immunohistological data. Treatment is based on high-dose corticosteroids with subsequent de-escalation. This treatment is usually effective initially but disease flares are frequent. Rheumatologists should suspect IgG₄-related systemic disease in patients referred to exclude connective tissue disease because of repeated inflammatory processes in distinct sites of localization.