The American College of Rheumatology (ACR) and European League Against Rheumatism have presented a draft of “Classification Criteria for IgG4-related Disease,” the first classification criteria developed for the recently recognized disease. The criteria were unveiled during a session at the annual meeting, and they are under review by both associations for endorsement.
According to the National Institutes of Health’s Genetic and Rare Diseases Information Center, immunoglobulin G4-related disease (IgG4-RD) is an immune-mediated condition that can affect multiple organ systems. Common features include IgG4-related autoimmune pancreatitis, swelling in an organ system, salivary gland disease, lymphadenopathy, skin manifestations, and symptoms consistent with allergies or asthma. The cause of the disease is unknown, but some researchers believe it may be an autoimmune or allergic disorder.
John H. Stone, MD, MPH, of Massachusetts General Hospital, who directed the panel of experts who developed the new criteria, said IgG4-RD often mimics other diseases, such as Sjögren’s syndrome, pancreatic cancer, granulomatosis with polyangiitis, giant cell arteritis, and systemic lupus erythematosus.
Only recognized about a decade ago, IgG4-RD is estimated to affect 180,000 people in the United States and many more worldwide. “Many of these patients have undergone radical surgical procedures, such as modified pancreatectomies, because they were believed to have cancer,” Dr. Stone said. “Their physicians did not recognize that what they had was an inflammatory disorder that is a highly treatable condition.”
There is no single diagnostic test for IgG4-RD. Dr. Stone believes that classification criteria will help clinicians diagnose the disease in a timely fashion and also assist researchers who are studying therapies for the condition, as classification criteria will allow researchers to accurately identify patients for inclusion in investigations.
The new criteria outline a three-step process that assesses data from four domains: information from the patient’s clinical presentation, the results of blood tests or serology, radiological findings, and pathology data. They were validated in a large cohort of patients, the team said.
“IgG4-RD has started to come out of the woodwork. Rheumatologists are seeing it more often in their clinical practice and [are] being referred patients who have it,” Dr. Stone said. “Few other diseases require such careful synthesis of different types of information in order to arrive at the correct diagnosis.”