Aims To investigate the frequency of IgG4-related disease (IgG4-RD) among patients previously diagnosed with idiopathic sclerosing orbital inflammation (ISOI), and to compare the clinical features and treatment outcomes of patients with ISOI associated with IgG4-RD and those without IgG4.

Methods Retrospective clinicopathological series of 24 patients with ISOI diagnosed between June 2001 and June 2010. Biopsy specimens were immunostained for IgG-expressing and IgG4-expressing cells. Clinical data of patients with IgG4-RD and ISOI unrelated to IgG4 were obtained from patient records.

Results Of 24 patients, 11 patients (45.8%) were identified with IgG4-RD. 10 patients (10/11, 90.9%) presented with bilateral lacrimal gland enlargement, and seven of those also had submadibular gland enlargement. One patient (1/11, 9.1%) presented with a superior orbital mass. All patients were successfully treated with steroids and/or radiotherapy or had an indolent clinical course. 13 patients (54.2%) were identified with ISOI unrelated to IgG4. Eight patients (8/13, 61.5%) showed unilateral orbital involvement, and nine patients (9/13, 69.2%) had orbital lesions not involving the lacrimal glands. Treatment modalities for ISOI unrelated to IgG4 were varied and less effective: eight patients (61.5%) relapsed following initial treatment with steroids or radiation, and additional therapies were required to enter remission.

Conclusions IgG4-RD may be identified frequently in patients with ISOI, and distinguishing features may be bilateral lacrimal gland enlargement with associated submandibular gland enlargement. Patients with IgG4-RD may have better treatment outcomes with less aggressive treatment modalities than those with ISOI unrelated to IgG4. An additional workup for IgG4-RD should be considered in all histopathological biopsy specimens suspicious of ISOI.