The spleen in Felty's syndrome: a histological, morphometrical, and immunohistochemical study.

A histological study employing morphometrical and immunohistochemical methods was performed in 3 spleens removed because of Felty's syndrome (FS). A comparison was made with control spleens and with spleens removed from patients with idiopathic thrombocytopenic purpura (ITP) or autoimmune hemolytic anemia (AIHA). In FS, the spleen is enlarged, mainly due to expansion of the red pulp. The sinuses are enlarged, too, and contain many macrophages. 2 of our specimens showed many hyperplastic germinal centers; the 3rd contained no germinal centers. Only in the former cases did splenectomy lead to an increase in the number of circulating granulocytes. Immunohistologically, FS spleens differed from the control, the ITP, and the AIHA spleens. The results have provided further evidence indicating that the pathogenesis of granulocytopenia in FS differs from that of autoimmune hematocytopenias, and have given rise to the hypothesis that, in FS, the spleen is the site of interaction between immune complexes and granulocytes.