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IgG4-related diseases are immune diseases that cause inflammation and lumps in organs throughout the body. Since this disease resembles cancer, there are cases in which the organ is removed by mistake, so it is important to undergo a detailed examination by a specialist to make a differential diagnosis.

Systemic organ lumps in IgG4-related diseases have been known for some time, but have been treated as separate diseases. However, around 2001, Dr. Terumi Kanzawa of the Department of Gastroenterology (current director) of the Cancer and Infectious Diseases Center Komagome Hospital, et al. We discovered that there were many lumps, and confirmed that many cells secreting the immune-related substance IgG4 were infiltrating these tissues. Furthermore, it was clarified that inflammation occurred in systemic organs as IgG4 levels increased, and that these symptoms improved with steroid treatment. In 2003, we proposed the concept of a new disease called IgG4-related disease based on research results showing these commonalities. Since then, it has attracted international attention, and many international symposiums on IgG4-related diseases have been held.

IgG4-related diseases are thought to be caused by abnormalities in the immune system that protects the body from pathogens. Typical examples include autoimmune pancreatitis and Mikulicz disease, which causes visual impairment due to swelling of the lacrimal and salivary glands. Lumps can occur in various organs, including the pituitary gland, lacrimal gland, salivary gland, thyroid gland, lung, hilar lymph node, bile duct, kidney, pancreas, abdominal aorta, and prostate. It is said that there is also the case of an organ. The average age of onset patients is about 60 years old, and the number of patients nationwide is estimated to be about 8,000 to 15,000, and it has been found that there are many elderly male patients. It is also designated as a national intractable disease. However, there are many things that are not well understood, such as the mechanism of onset, and research on the cause and onset mechanism continues.

Diagnosis is made by considering imaging findings such as organ lumps and high IgG4 levels in the blood. Symptoms may include jaundice, which turns the skin yellow, dry eyes, where the amount of tears is insufficient, and dry mouth, where the amount of saliva is decreased and the mouth feels dry (although these two symptoms may occur, It is known to occur much less frequently than Sjögren's syndrome, which must be differentiated.The main symptom is swelling of the eyelids and lower jaw on both sides.) A lump in an organ is often mistaken for cancer, and there have been reports of cases in which a patient was previously diagnosed with pancreatic cancer and underwent resection, resulting in autoimmune pancreatitis. Treatment is with oral steroids to reduce inflammation. “Even now, depending on the symptoms, it can be mistaken for cancer, so it is important to have a detailed examination by a specialist to make a differential diagnosis,” emphasizes Mr. Kanzawa.