Sinus histiocytosis with massive lymphadenopathy: evidence for its relationship to macrophages and for a cytokine-related disorder.

AIMS: Sinus histiocytosis with massive lymphadenopathy (SHML) or Rosai-Dorfman disease is a rare histiocytic disorder of unknown origin. Immunophenotypically the histiocytes of SHML express intensively the S100 protein and in addition a panel of macrophage-associated antigens. Their exact relationship to either monocytes/macrophages or immune accessory dendritic cells is, however, still controversial. METHODS AND RESULTS: In this report recurrent nodal and extranodal manifestations of SHML of a 70-year-old patient were analysed by differential phenotyping using a panel of monoclonal and polyclonal antibodies to macrophage and immune accessory dendritic cell related antigens and by applying nonradioactive in-situ hybridization. CONCLUSIONS: We conclude that stimulation of monocytes/macrophages via macrophage colony stimulating factor (M-CSF) leading to immune suppressive macrophages represents a main mechanism for the pathogenesis of SHML. The study further provides evidence for the monocyte/macrophage but not dendritic cell differentiation of SHML histiocytes.