Background: Mikulicz's disease (MD) has been considered as one manifestation of Sjögren's syndrome (SS). Recently, MD has also been considered as an IgG4-related disorder.
Objective: To determine the differences between IgG4-related disorders including MD and SS. Patients and Methods: We investigated patients with MD and IgG4-related disorders registered from all over Japan, and set up provisional criteria for the new clinical entity: IgG4-positive multi-organ lymphoproliferative syndrome (IgG4+MOLPS). The preliminary diagnostic criteria include elevated serum IgG4 (>135 mg/dl) and infiltration of IgG4+ plasma cells in the tissue (IgG4+/IgG+ plasma cells >50%) with fibrosis or sclerosis. We compared clinical features, laboratory data and pathologies of 64 patients with IgG4+MOLPS and 31 patients with typical SS.
Results: The incidences of xerostomia, xerophthalmia and arthralgia, rheumatoid factor and anti-nuclear, anti-SS-A/Ro and anti-SS-B/La antibodies were significantly lower in IgG4+MOLPS than typical SS patients. Allergic rhinitis and autoimmune pancreatitis were significantly more frequent and total IgG, IgG2, IgG4 and IgE were significantly elevated in IgG4+MOLPS. Histological specimen from patients with IgG4+MOLPS revealed marked IgG4+ plasma cell infiltration. Many patients with IgG4+MOLPS showed lymphocytic follicle formation, but lymphoepithelial lesions were rare. Few IgG4+ cells were seen in the tissue of typical SS. Thirty-eight patients with IgG4+MOLPS treated with glucocorticoids showed marked clinical improvements.
Conclusion: Despite similarities in the involved organs, there are marked clinical and pathological differences between IgG4+MOLPS and SS. Based on the clinical features and good response to glucocorticoid, we propose a new clinical entity: IgG4+MOLPS.