Recognizing IgG₄-Related Disease and Its Myriad Clinical Manifestations

IgG₄-related disease (IgG₄-RD) originally was described in Japan about a decade ago and is now considered in the differential diagnosis of multiple clinical presentations, including autoimmune pancreatitis, retroperitoneal fibrosis, idiopathic aortitis, and Mikulicz syndrome. Many clinicians believe that the clinical hallmark of diagnosis is simply an elevated IgG₄ level. However, IgG₄-RD can be confirmed only by characteristic studies (e.g., sausage pancreas in autoimmune pancreatitis) or, preferably, by the histopathological features (in specimens other than lymph node) of dense lymphocytic infiltrate, storiform fibrosis, and obliterative phlebitis, along with mild tissue eosinophilia and increased numbers of IgG₄-positive plasma cells.

In…