IgG4-related systemic disease

IgG-4 related systemic disease, hyper-IgG4 disease

Normally, IgG4 accounts for not more than 6% of the total IgG serum level. Hyper-IgG4 disease has been proposed as a unifying concept applicable to fibro-inflammatory diseases occuring at various anatomical sites. The prototype IgG-4 related disease is autoimmune pancreatitis. Other sites at which this condition has been reported include gallbladder, bile duct, stomach, colonic mucosa, mesentery, peritoneum, retroperitoneum, liver, lymph node, neck, salivary glands, orbit, kidney, prostate, breast, aorta, mediastinum, pituitary, bone marrow, lung, pleura, brain and thyroid. It is characterised by an infiltrate of IgG4-positive lymphoplasmacytic cells and exuberant fibrosis. The number of IgG4-posiitve cells may be assessed by either the number per high power field or the IgG4/IgG ratio.

Synonyms and site-specific terms

Pseudotumour, myofibroblastic tumour, plasma cell granuloma, systemic fibrosis, xanthofibrogranulomatosis, multifocal fibrosclerosis, retroperitoneal fibrosis, Reidel's thyroiditis, sclerosing / autoimmune pancreatitis, Fibrous pseudotumour of the orbit, Chronic sclerosing sialadenitis, Kuttner's tumour, Panniculitis, Weber-Christian syndrome steatonecrosis, necrosing panniculitis, bronchiolitis obliterans with organizing pneumonia, cryptogenic organizing pneumonia, pulmonary hyalinizing granuloma, benign pleural mesothelioma, calcifying pseudotumour

Some cases of retroperitoneal fibrosis are likely a manifestation of IgG4 disease. Male gender, raised serum IgG4, the presence of eosinophils within the lesion and obliterative phlebitis favour IgG4 disease2.

Clinical features

During the acute phase, there is fever and a high serum IgG4 level.

Management

Glucocorticoid steroid treatment

References

1 Neild GH, Rodriguez-Justo M, Wall C, Connolly JO. Hyper-IgG4 disease: report and characterisation of a new disease. BMC Med. 2006;4:23 FULL TEXT