IgG4-related disease presenting as a paraneoplastic syndrome: report of two cases and literature review

An association between immunoglobulin G4-related disease (IgG4-RD) and malignancy has been suggested. We report two cases of IgG4-RD with suspected paraneoplastic syndrome. In both patients, malignancy was observed immediately after diagnosis of IgG4-RD, and surgical resection resulted in spontaneous regression of IgG4-RD. We review the reports on IgG4-RD associated with malignancy, including these two cases, and discuss their relevance.