Recent topics in IgG4-related disease

Abstract

IgG4-related disease (IgG4-RD) is a chronic inflammatory disorder, characterized by organ enlargement and mass-forming or nodular/thickened lesions, and elevated serum IgG4 levels as well as abundant infiltration of IgG4-positive plasmacytes with fibrosis in various organs, including the head and neck region. Over 15 years after Mikulcz’s disease was recognized as a clinical and pathological entity distinct from Sjögren’s syndrome, the diagnostic criteria of IgG4-retaled dacryoadenitis and sialadenitis (IgG4-DS) has been revised. Only one lesion is also diagnosed by this new criteria, and labial salivary gland biopsy is able to be used for diagnosis in IgG4-DS patients. IgG4-DS typically affects middle-aged to elderly men, and the sex-ratio of patients with IgG4-DS is roughly equal. Ultrasonography may be useful for detection of IgG4-DS of salivary glands. The differentiation of IgG4-RD from not only malignant diseases but also common conditions mimicking IgG4-RD is important. IgG4-RD is also found to affect sinonasal lesion (including olfactory dysfunction), hypertrophic pachymenigitis, and thyroid gland. In particular, the diagnostic criteria of IgG4-related thyroid disease is revised recently, and further studies with more patients are needed. Among the organs involved in IgG4-RD, recent immunological studies suggest the existence of autoantibodies and target antigens. Further studies of the pathophysiology of IgG4-DS are warranted.