Immunohistochemical study of so-called sclerosing haemangioma of the lung

To elucidate the histogenesis of sclerosis haemangioma of the lung, we examined 7 cases with the immunoperoxidase method using antibodies against several useful marker antigens; secretory component (SC), cytokeratins, epithelial membrane antigen (EMA) for epithelial cells, factor VIII related antigens (factor VIII) for endothelial cells, vimentin and desmin for mesenchymal cells. The results were compared with those of histologically normal lung tissues. Both the characteristic round cells arranged in sheets, which are present predominantly in the solid area and are reported to be neoplastic, and the flattened cells lining blood lakes show positive staining for EMA only, with negative staining for the other marker antigens. These observations suggest that these cells are derived from epithelium rather than mesothelium or from endothelium, and are analogous to type I pneumocytes. This conclusion is supported by their immunohistochemical characteristics, in comparison with the localization patterns of the marker antigens in normal lung tissues. However, the lining epithelial cells of papillary projections in the papillary area and of ducts in the solid area stained for SC and cytokeratins as well as EMA, and their immunohistochemical characteristics are analogous to those of bronchiolar epithelial cells or type II pneumocytes in normal lung tissues.