IgG4-related Disease

IgG4-related Disease is a condition where the body's immune system causes inflammation and swelling in various organs. It can affect many parts of the body, including the pancreas, salivary glands, kidneys, and lymph nodes. This disease leads to the formation of tumor-like masses or tissue thickening, which can interfere with normal organ function. The inflammation is caused by an increase in a specific type of antibody called IgG4. Symptoms depend on which organs are involved but often include swelling, pain, or organ dysfunction. Because it can affect multiple systems, it is considered a systemic disease. Early diagnosis is important to prevent permanent damage to affected organs.

IgG4-related Disease is a systemic fibroinflammatory condition characterized by dense lymphoplasmacytic infiltrates rich in IgG4-positive plasma cells, storiform fibrosis, and often elevated serum IgG4 levels. The pathogenesis involves an abnormal immune response with infiltration of IgG4-secreting plasma cells and T-helper 2 cell cytokines leading to chronic inflammation and fibrosis. It commonly affects the pancreas (autoimmune pancreatitis), salivary glands (sialadenitis), and other organs, causing tumefactive lesions that mimic malignancy or infection. The disease is significant due to its potential to cause organ dysfunction and fibrosis if untreated. Diagnosis requires integration of clinical, serologic, radiologic, and histopathologic findings. It is important to distinguish it from malignancies and other inflammatory diseases because it responds well to immunosuppressive therapy.