Sclerosing hemangioma of the lung. Immunohistochemical characterization of its origin as related to surfactant apoprotein.

Lung tissues from 13 patients with pulmonary sclerosing hemangioma were studied with antibody against surfactant apoprotein, Factor VIII-related antigen, or lysozyme. Surfactant apoprotein was detected in the cytoplasm of the cells lining cystic spaces and papillary projections. Surfactant apoprotein was found in a small number of stromal cells with abundant eosinophilic or clear cytoplasm and round to oval nuclei, which were characteristic in pulmonary sclerosing hemangioma as the main component. Surfactant apoprotein was also found in the stromal cells with small, dark nuclei similar to the lining cells. The lining and stromal cells contained neither Factor VIII-related antigen nor lysozyme. Our demonstration of surfactant apoprotein in these cells provides further support for the idea that pulmonary sclerosing hemangioma primarily consists of epithelial cells with differentiation to type II pneumocytes, as was deduced from ultrastructural investigations.