Relationship between rosai-dorfman disease and IgG4-related disease: Study of 32 cases

Objectives: To assess the association between Rosai- Dorfman disease (RDD) and IgG4-related disease (IgG4-RD). Methods: We studied the number of IgG4-positive plasma cells and the IgG4/IgG ratio in 32 biopsy specimens (13 nodal, 19 extranodal) from 29 patients with RDD and compared the findings with those in IgG4-RD of the pancreas and reactive lymph nodes. We also assessed the number of FOXP3-positive regulatory T cells (Tregs) since they were reported to be increased in IgG4-RD. Results: We found that RDD cases had much lower numbers of IgG4-positive plasma cells and lower IgG4/IgG ratios compared with IgG4-RD but were similar to reactive lymph nodes. Furthermore, RDD had lower numbers of FOXP3- positive Tregs than did IgG4-RD. There were no significant differences in the number of IgG4-positive plasma cells and the IgG4/IgG ratio between the nodal and extranodal RDD cases. Conclusions: Our study suggests that RDD does not belong in the spectrum of IgG4-RD.