IGHE and immunoglobulin G4-related sclerosing disease: Indeed, peripheral blood eosinophilia, elevated serum immunoglobulin E (IgE), and IgG4 at disease onset have traditionally been proposed as predictors of recurrence, but a better understanding of the natural history of IgG4-RD has gradually unveiled the shortcomings of these biomarkers [1, 2, 5, 6].