Clinical and pathological characteristics of Mikuliczʹs disease (IgG4-related plasmacytic exocrinopathy)

Mikuliczʹs disease (MD) has been considered part of primary Sjögrenʹs syndrome (SS) since Morganʹs report in 1953. MD represents a unique condition involving enlargement of the lacrimal and salivary glands, as is also seen in SS; however, MD is characterized by few autoimmune reaction and its good responsiveness to glucocorticoid. Recent reports have shown that the frequency of apoptosis in glands of MD patients is lower when compared with SS. This phenomenon reflects the histologically reversible gland secretion in MD. Elevated IgG4 concentrations in the serum and prominent infiltration by plasmacytes expressing IgG4 in the lacrimal and salivary glands have also been confirmed in MD. Plasma cells expressing IgG4 are also detected in lymph nodes and bone marrow. MD may be a systemic disease, rather than a lacrimal and salivary gland disease. We here propose the new entity “IgG4-related plasmacytic exocrinopathy” and expect future development with regard to its relationship with autoimmune pancreatitis, which similarly presents elevated serum IgG4 levels.