Histological, ultrastructural, morphometric and immunohistochemical data obtained from the study of spleens removed by
splenectomy from 34 patients with advanced hepatosplenic
schistosomiasis revealed that the main alterations were congestive dilatation of the venous sinuses and diffuse thickening of the splenic cords. Splenic cord thickening was due to an increase of its matrix components, especially
type IV collagen and
laminin, with the conspicuous absence of interstitial
collagens, either of type I or type III. Deposition of interstitial
collagens (types I and III) occurred in scattered, small focal areas of the red pulp, but in the outside of the walls of the venous sinuses, in lymph follicles, marginal zone, in the vicinity of fibrous trabeculae and in sidero-sclerotic nodules. However,
fibrosis was not a prominent change in schistosomal
splenomegaly and thus the designation "fibro-congestive
splenomegaly" seems inadequate. Lymph follicles exhibited variable degrees of
atrophy,
hyperplasia and fibrous replacement, sometimes all of them seen in different follicles of the same spleen and even in the same examined section. Changes in white pulp did not seem to greatly contribute to increasing spleen size and weight, when compared to the much more significant red pulp enlargement.