Clinical characteristics of Mikulicz's disease as an IgG4-related disease

Mikulicz's disease (MD) was considered to be a subtype of Sjogren's syndrome (SS), based on histopathological similarities. However, recent studies have indicated that patients with MD show high serum IgG4 concentration, and suggested that MD is one of IgG4-related disease and distinguishable from SS. Therefore, we clinically and histopathologically examined the disease states of MD and SS in detail. Twenty patients with Mikulicz's disease and 18 with SS were comparatively studied to determine clinical characteristics in MD patients. Sialography in MD patients did not show the apple-tree sign typically seen in SS. Serologically, high serum IgG4 levels but not anti-SS-A or anti-SS-B antibodies were observed in MD. SS showed lymphocytic infiltration of various subsets with atrophy or severe destruction of the acini, while MD showed selective infiltration of IgG4+ plasma cells with hyperplastic germinal centers and mild acini destruction. Corticosteroid treatment of MD reduced IgG and IgG4 levels and improved salivary function. A negative correlation between disease duration and increasing rate of salivary flow was observed in MD. These results suggested that the pathogenesis of MD might be different from those of SS. Clinical Relevance: early diagnosis and treatment of MD is important for the improvement of salivary function.