Horie, Ryohei

ObjectiveTo investigate clinical and pathologic aspects of IgG4‐related disease (IgG4‐RD) in non‐Asian populations.MethodsWe conducted a retrospective review of the medical records of patients with IgG4‐RD who presented to an academic medical center from January 1994 to September 2012.ResultsAmong 166 patients identified, the median age at diagnosis was 61 years (interquartile range [IQR] 49–70 years), 75% were male, and 80% were white. The median number of organs involved was 2 (IQR 2–3). When organs were grouped according to anatomic system, the hepatopancreaticobiliary system was most commonly involved (77%). The median highest serum IgG4 level during the clinical course was 215 mg/dl (IQR 122–466). Forty‐three patients (26%) had a normal serum IgG4 level. Seventy‐nine pathology specimens were available for immunostaining. The median number of IgG4+ cells was 37 (IQR 25–82) per high‐power field, with an IgG4+:IgG+ ratio of 0.50 (IQR 0.32–0.68). Among 151 patients who received medical therapy, 72 (48%) received steroid‐sparing agents because of relapse, recurrence, or corticosteroid intolerance. Of the 66 patients who were newly diagnosed, started on corticosteroid monotherapy as the initial treatment, and followed up at our institution, 30 (45%) experienced relapse or recurrence despite an initial favorable response. The number of organs involved had a significant impact on time to relapse or recurrence, with a hazard ratio of 1.48 (95% confidence interval [95% CI] 1.12–1.93) (P < 0.01) in multivariate analysis. The standardized incidence ratio of malignancy was 4.5 (95% CI 1.5–7.5).Conclusion. IgG4‐RD is a multisystem disorder that commonly affects older men and has a propensity for relapse, recurrence, and malignancy.

IgG4-related disease (IgG4-RD) is a recently described systemic fibroinflammatory disease associated with elevated circulating levels of IgG4 and manifests a wide spectrum of clinical presentations. Although serum IgG4 level has been described to be the most sensitive and specific laboratory test for the diagnosis of IgG4-RD, it is recognized that an elevated serum IgG4 level can be encountered in other diseases. In this study, we sought to identify the frequency of IgG4-RD and other disease associations in patients with elevated serum IgG4 levels seen in clinical practice. Among 3,300 patients who underwent IgG subclass testing over a 2-year period from January 2009 to December 2010, 158 (4.8%) had an elevated serum IgG4 level (>140 mg/dL). IgG4 subclass testing was performed for evaluation of suspected IgG4-RD or immunodeficiency. Twenty-nine patients (18.4%) had definite or possible IgG4-RD. Among those patients without IgG4-RD, a broad spectrum of biliary tract, pancreatic, liver, and lung diseases, as well as systemic vasculitis, was diagnosed. We conclude that patients with elevated serum IgG4 levels encountered in clinical practice manifest a wide array of disorders, and only a small minority of them has IgG4-RD.