IgG4-related disease (IgG4-RD) is an autoimmune disorder in which patients have elevated blood levels of IgG4, the most common form of immunoglobulin that circulates in the blood. Increased levels of IgG4 can cause inflammation in a single organ or in multiple organs, such as the meninges (tissue surrounding brain and spinal cord), the eye sockets, lacrimal (tear duct) glands, salivary glands, thyroid gland, lungs, aorta, kidneys, bladder, pancreas, and bile ducts. IgG4-related disease most often affects middle-aged and elderly males, and rarely, children.

Symptoms of IgG4-related disease are many and varied, depending on the affected organ; however, some common symptoms include fatigue, the appearance of a tumor that mimics cancer, and allergies, such as asthma, allergic rhinitis, and eczema. Patients may have an active IgG4-related disease for months or years with no signs or symptoms, even while organ damage is occurring. A significant weight loss (10-50 pounds) may be a presenting symptom. Symptoms of IgG4-related disease that depend on which organ is affected may include headaches, cranial nerve dysfunction, abnormal eye movements, speech, swallowing, or hearing (meninges); bulging of one or both eyes (proptosis), double vision, or eye muscle disorders (orbits); enlarged tear ducts (lacrimal glands); bulges on the sides of face or below chin, excessive saliva, or dry mouth (salivary glands); enlarged thyroid (Riedel’s thyroiditis) and airway compromise (thyroid gland); allergy, shortness of breath, and pleuritis (lungs); aortic lesions or aortic aneurysm; hydronephrosis (urine blockage) or kidney injury; painless jaundice (yellowing of eyes and skin), pancreatitis, and diabetes mellitus; and bile duct lesions.

The current treatments for IgG4-related disease are glucocorticoids or rituximab.