FOXP3 and sinus histiocytosis with massive lymphadenopathy: However, others consider that RDD is not a kind of IgG4-RD because in affected tissues, IgG4 + plasma cells, IgG4/IgG proportion and foxp3 + Tregs are still lower than those in classic IgG4-RD but similar to those in reactive hyperplastic lymph nodes [10].