A case of marginal zone B cell lymphoma mimicking IgG4-related dacryoadenitis and sialoadenitis

Background IgG4-related dacryoadenitis and sialoadenitis (IgG4-DS), so-called Mikulicz’s disease, is characterized by elevated serum IgG4 and infiltration of IgG4-positive plasma cells in glandular tissues. Recently, several studies reported both malignant lymphoma developed on the background of IgG4-associated conditions and IgG4-producing malignant lymphoma (non-IgG4-related disease).