Abstract
BACKGROUND: To identify the prevalence of positive IgG4 immunostaining in orbital tissue among patients previously diagnosed with nongranulomatous idiopathic orbital inflammation (IOI) and to compare the clinical characteristics of patients with and without IgG4-positive cells. METHODS: A retrospective review of all patients with a histopathologic diagnosis of IOI was performed. Immunohistochemical staining was performed to identify IgG-positive cells and IgG4-positive cells. Multivariate analysis was performed using likelihood ratio-test logistic regression on the differences between IgG4-related disease (IgG4-RD) and non-IgG4-RD. RESULTS: Of the 45 patients included, 21 patients (46.7%) had IgG4-positive cells, with 52.4% being male and a mean age of 55.9 ± 13.4 years. Bilateral ocular adnexal involvement (adjusted odds ratio [aOR] = 9.45; P = 0.016) and infraorbital nerve enlargement (aOR = 12.11; P = 0.008) were frequently found in IgG4-RD patients. Complete remission occurred in 23.8% of IgG4-RD patients and 41.7% of non-IgG4-RD patients. IgG4-RD patients had more frequent recurrent disease than non-IgG4-RD patients. CONCLUSIONS: Nearly 50% of IgG4-RD patients were previously diagnosed with biopsy-proven IOI. IgG4-RD was more frequent in patients with bilateral disease and infraorbital nerve enlargement, showing the importance of tissue biopsy in these patients. Immunohistochemistry studies of all histopathology slides showing nongranulomatous IOI are highly recommended to evaluate for IgG4-RD.