A Spotlight on IgG4-Related Disease

Figure 5: This PET study demonstrates diffuse uptake within both parotid glands and lymph nodes throughout the axillae and mediastinum.

Summary

Our patient had a multiorgan system disease of at least two years’ duration characterized by tubulointerstitial nephritis, salivary gland enlargement, jaundice, diffuse lymphadenopathy, and an elevated erythrocyte sedimentation rate. In addition, it is likely that his pancreatitis, which led to glucose intolerance, was in fact IgG4-related (type 1) autoimmune pancreatitis. He was misdiagnosed with a number of other conditions before the correct diagnosis of IgG4-RD was recognized.

IgG4-RD is a newly recognized entity, but in fact it is an old one. The disease can involve multiple organ systems, frequently in a metachronous fashion (i.e., first one organ, then another, and then another). The disease tends to cause mass-forming lesions that can mimic cancer, infections, and rheumatic conditions such as granulomatosis with polyangiitis (Wegener’s) and SS. This disease is responsible for substantial percentages of cases—and sometimes all cases—of a variety of clinical entities previously referred to by other names (e.g., retroperitoneal fibrosis, Riedel’s thyroiditis, Mikulicz disease, Küttner’s tumor, and others).

Most patients respond well to glucocorticoids, but many are unable to discontinue these medications without disease recurrence. B-cell depletion is a promising treatment strategy now under investigation.

Follow-up

Because of his glucose intolerance and the extensive nature of his disease, we treated our patient with rituximab 1 gram intravenously given on two separate occasions. Within one month of his first dose, his parotid gland swelling had resolved, and his serum IgG4 concentration had declined by more than 600 mg/dL. He is currently enrolled in an ongoing clinical trial.

Dr. Atac is a visiting researcher at the Massachusetts General Hospital. Dr. Stone is a professor of medicine at Harvard Medical School and director of clinical rheumatology at Massachusetts General Hospital in Boston.

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