Enfermedad relacionada con IgG4

Abstract

Immunoglobulin G4-related disease (IgG4-RD) is a fibro-inflammatory condition that can involve all the systems of the organism. This disease has been described relatively recently, in the early decades of the 21st century. Due to this, its aetiology and pathophysiology are not currently sufficiently established. Proof has been growing that the pathogenesis of the disease has an autoimmune foundation, with participation of the memory B cells, T follicular helper (Tfh) cells, T CD4 lymphocytes and macrophages. Initially, the elevation of the IgG fraction 4 (IgG4) serum levels of these patients made it seem that they might be of value in aetiopatogenesis and diagnosis. However, it has later been seen that only about 60% of the patients present elevated serum IgG4 levels. Although almost any organ can be affected, predilections have been defined, principally the salivary glands, orbits and lacrimal glands, pancreas and biliary tree, lungs, kidneys, aorta and retroperitoneal area, meninges and thyroid gland. All the organs affected by IgG4-RD share several histopathological features: lymphoplasmocytic infiltrate with abundant positive IgG4 plasma cells, storiform fibrosis, obliterative phlebitis and eosinophil presence. Diagnosing is complex, given that it requires a combination of clinical, analytical, radiological and histopathological examination. Numerous differential diagnoses also have to be excluded.