Immunoreactivity of surfactant-apoprotein in adenocarcinomas, large cell and small cell carcinomas of the lung.

Fifty seven adenocarcinomas, 43 large cell and 30 small cell lung carcinomas were immunohistochemically examined using monospecific IgG against pulmonary surfactant apoprotein. Six peripheral adenocarcinomas and one peripheral large cell carcinoma were found to be histogenetically related to type II pneumocytes. They showed an acinar, papillary or solid growth pattern. The immunohistochemical study using anti-surfactant apoprotein IgG gave a granular reaction product in both the cytoplasm and nucleus of tumor cells whose intensity was variable. Intranuclear inclusions were generally the most densely stained structures. These results suggest that lung carcinomas derived from alveolar type II cells are found not only in bronchioloalveolar tumors, but are also found in other types of adenocarcinoma and in large cell carcinomas.