Hamartomas of the spleen: a study of 20 biopsy cases.

Twenty hamartomas of the spleen were studied by histological, immuno- and enzyme-histochemical methods. In all cases nodules of varying size resembling proliferation of splenic red pulp structures were present that exhibited considerable morphological variation with regard to plasmacytosis, extramedullary haematopoiesis and phagocytic activity of macrophages. Splenic red pulp structures could be identified by immuno- and enzyme-histochemical markers reacting with sinus endothelium, including Factor VIII related antigen, proteinase inhibitors and non-specific esterases. In conjunction with the absence of organized lymphoid tissue and of dendritic reticulum cells these studies allow the differentiation of splenic hamartomas from haemangiomas that may possess a deceptively similar morphological appearance.