IgG4-related disease: a rheumatologist's perspective.

Objectives: Given that the clinical features of several IgG4-related diseases (IgG4-RD) can mimic those of autoimmune disorders, the aim of this study was to find possible distinguishing characteristics that would help us identify such cases from the pool of patients in a rheumatology clinic.
Methods: From our clinic's medical records, we identified patients who fulfilled the recently published diagnostic criteria for IgG4-RD. We recorded their presenting features, co-morbid conditions, laboratory, radiologic and histologic findings as well as their treatment and outcome.
Results: We identified 11 cases of IgG4-RD: 4 cases of IgG4-related autoimmune pancreatitis (AIP), 5 cases of IgG4-related retroperitoneal fibrosis (RPF)/ periaortitis, 2 cases of IgG4-related sialadenitis and one of IgG4-related interstitial nephritis. 5 out of the 11 patients had been diagnosed with an autoimmune disease, namely rheumatoid arthritis (RA), Sjogren's syndrome (SS) and antiphospholipid syndrome (APS). 3 out of 11 patients were subsequently diagnosed with neoplastic disorders. All patients with IgG4-related AIP had raised CRP levels at presentation. Presenting features of RPF/periaortitis patients were constitutional symptoms, abnormal renal function, hypertension and back pain. Patients with IgG4-related sialadenitis had clinical features mimicking SS. The majority of patients had a favourable response to steroids.
Conclusions: We present common IgG4-RD presentations in the setting of a rheumatology clinic. Increased awareness may avoid delay in diagnosis.