This study was to determine the prevalence of immunoglobulin G4 (IgG4)-related orbital disease (IgG4-ROD) among patients who have previously undergone biopsy and were diagnosed to have idiopathic orbital inflammatory disease (IOID) or orbital lymphoproliferative disease (OLD), namely, lymphoma and benign reactive lymphoid hyperplasia (BRLH). This is a retrospective cross-sectional study. The charts and slides of all patients who underwent biopsies and were histopathologically diagnosed to have either IOID or OLD were reviewed. Demographics, clinical features, initial histopathological diagnoses, treatment received, and final outcome were noted. Using the diagnostic criteria for diagnosis for IgG4 disease, those cases that would classify as "possible IgG4-related disease (IgG4-RD)" were reviewed, reclassified, and reassigned a diagnosis of IgG4-ROD. We reviewed 105 patients' clinical charts. Of these 105 patients, upon reviewing the histopathology, 18 (17.15%) patients were found to fit the diagnostic criteria for possible IgG4-ROD. Of these 18 patients who were now reassigned the diagnosis of IgG4-ROD, the most common previous histopathological diagnosis was found to be IOID, for eight patients (44%), then BRLH, which was noted in five patients (27.8%), followed by lymphoma, which was noted in two patients (11.1%). Previously diagnosed cases of IOID and OLD were found to fulfill the criteria for IgG4-ROD. Given the advent of recent diagnostic and histopathological techniques, all cases of suspected IOID and OLD should be screened for IgG4-ROD and all previously diagnosed cases must be closely followed up, given the systemic implication of IgG4-RD. Histopathological reassessment of previously diagnosed cases may be considered.
Keywords: IgG4-related orbital disease; lymphoma; nonspecific orbital inflammation; orbit.