Orbital IgG4 Related Disease (IgG4RD): Incidence and Accompanying Histological Features Using the Latest Consensus Criteria

Abstract

Purpose: Orbital Immunoglobulin 4 (IgG4) related disease (IgG4RD) is a fibro-inflammatory condition that mimics sclerosing orbital inflammatory disease (OID). The recently published IgG4RD consensus criteria included its defining histological features. Using the published criteria, this study aims to describe the frequency of orbital IgG4RD and its histological features in OID biopsies over a 1 year period. Method: Thirty-seven consecutive orbital biopsies for OID over 1 year were prospectively examined for the features of fibrosis, inflammation, and vasculitis. Immunohistochemistry (IHC) evaluation was performed when significant fibrosis and/or lymphoplasmacytic inflammation ( >25% of the biopsy section) was present. Results: Ten of 37 (27%) orbital biopsies showed significant fibrosis and/ or lymphoplasmacytic inflammation with the remaining cases showing only non-specific chronic inflammation or reactive lymphoid hyperplasia. Only 3 cases (30%) fulfilled the IgG4RD consensus criteria. The histological patterns included sclerosing dacroadenitis, sclerosing xanthogranulomatous orbital inflammation, and eosinophilic angiocentric fibrosis. Storiform fibrosis was the most common histological feature present (70%), followed by dense lymphoplasmacytic inflammation (60%). When both are present, an almost 2-fold elevation of tissue IgG4 plasma cells and ratio above the diagnostic cut-off was detected. Xanthogranulomatous inflammation and eosinophilia were occasionally present. Conclusions: Using the consensus criteria, IgG4RD was diagnosed in 30% of our orbital biopsies with significant fibrosis and/ or inflammation and 11% of all OID biopsied in 1 year. Although the storiform fibrosis and lymphplasmacytic inflammation was most commonly seen, associated eosinophilia and xanthogranulomatous inflammation may also be seen in IgG4RD.