IgG4-Related Disease: Navigating Diagnosis and the Expanding B-Cell-Targeted Treatment Landscape - Episode 1
Understanding IgG4-RD: Definition, Epidemiology, and Multi-Organ Presentation
IgG4-related disease can involve almost any organ and often begins without symptoms. The panel defines the condition, outlines who it affects, and describes the many ways it presents.
Welcome back to another HCPLive Peer Exchange series. In "Understanding IgG4-RD: Definition, Epidemiology, and Multi-Organ Presentation," moderator Emma Culver, BSc, MBChB, MRCP, DPhil is joined by Emanuel Della Torre, MD, PhD and Guy Katz, MD to open the series on IgG4-related disease.
Dr. Culver, a gastroenterologist and hepatologist in Oxford, begins by asking Dr. Della Torre to define the condition. He describes IgG4-related disease as a fibroinflammatory condition that can affect virtually any organ system. It typically presents as a triad of tumor-like mass-forming lesions, elevated serum IgG4, and characteristic pathology. The lesions resemble cancers but are not malignant. The disease takes its name from IgG4 elevation in serum and in tissue, where affected organs share a dense infiltrate of IgG4-expressing B-lineage cells.
On epidemiology, Dr. Della Torre notes that the disease remains rare, with a prevalence of no more than about 5 to 10 per 100,000 people. Men are affected more often than women, particularly in certain phenotypes. Women more often present with head and neck disease, while men more often have extracranial disease. As clinicians grow better at recognizing it, he predicts that IgG4-related disease may not be considered rare within a few years.
Dr. Katz explains why the disease is such a diagnostic challenge. In the head and neck, lacrimal, parotid, and submandibular glands may enlarge, sometimes with dry eyes or dry mouth. Often, however, the swelling is painless, symmetric, and asymptomatic. Autoimmune pancreatitis and sclerosing cholangitis are vital to recognize because of their high propensity for damage. The lungs, kidneys, prostate, retroperitoneum, and aorta can also be involved, as can the orbits, meninges, and thyroid.
In his experience, most patients have multi-organ disease, a pattern seen in cohorts worldwide. Single-organ disease is more typical of fibrotic manifestations such as retroperitoneal fibrosis, pachymeningitis, Riedel thyroiditis, and sclerosing mesenteritis. Inflammatory presentations, such as salivary gland disease, can occasionally occur alone. Still, most patients develop multi-organ involvement, if not at presentation, then during follow-up.
The next episode in this series, "IgG4-RD Mimics and the Manifestations That Require Urgent Treatment," features the panel separating IgG4-related disease from its many look-alikes and identifying which organ involvement cannot wait.
