Eosinophilic angiocentric fibrosis and immunoglobulin 4-related disease revisited.

Eosinophilic angiocentric fibrosis (EAF) has been postulated to lie on the spectrum of IgG4-related disease (IgG4-RD) in a study reported in 2011. However, the aetiology of EAF remains controversial, despite increasing literature reporting IgG4-RD targeted investigations in those studies. This review aims to formally evaluate the relationship between EAF and IgG4-RD using the latest 2019 American College of Rheumatology/European League Against Rheumatism (ACR/EULAR) classification scheme for IgG4-RD. A literature search was performed on the PubMed database for all studies describing patients diagnosed with EAF. Additionally, two EAF cases were retrospectively identified from our institution and presented. The demographics, clinical presentation, histological and serological data of each patient were analysed. A total of 20 cases were evaluated, including 18 patients from 14 articles in the English literature and two cases from our institution. Six of 20 (30%) patients with EAF met the criteria for IgG4-RD with the 2019 ACR/EULAR classification scheme. This represents the first attempt at formally evaluating the relationship between EAF and IgG4-RD using a validated set of classification criteria. Using the currently available data, a small proportion of patients with EAF met the criteria for IgG4-RD. However, various limitations of this study suggest that further efforts at disease characterization of EAF may be required.