Pathology of the spleen in hepatosplenic schistosomiasis. Morphometric evaluation and extracellular matrix changes

Histological, ultrastructural, morphometric and immunohistochemical data ob tained from the study of spleens removed by splenectomy from 34 patients wi th advanced hepatosplenic schistosomiasis revealed that the main alteration s were congestive dilatation of the venous sinuses and diffuse thickening o f the splenic cords. Splenic cord thickening was due to an increase of its matrix components, especially type IV collagen and laminin, with the conspi cuous absence of interstitial collagens, either of type I or type III. Depo sition of interstitial collagens (types I and III) occur-red in scatter-ed, 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 fibro us trabeculae and in sidero-sclerotic nodules. However; fibrosis was not a prominent change in schistosomal splenomegaly and thus the designation "fib ro-congestive splenomegaly" seems inadequate. Lymph follicles exhibited var iable degrees of atrophy, hyperplasia and fibrous replacement, sometimes al l of them seen in different follicles of the same spleen and even in the sa me examined section. Changes in white pulp did not seem to greatly contribu te to increasing spleen size and weight, when compared to the much more sig nificant red pulp enlargement.