Immunohistochemical study of pulmonary adenocarcinoma.

In order to improve the accuracy of diagnosis and subtyping of pulmonary adenocarcinomas, immunohistochemical studies were carried out on 105 adenocarcinomas of the lung procured from both surgery and autopsy. Avidin-biotin-peroxidase complex methods were used for identifying keratin, vimentin, carcinoembryonic antigen (CEA), and secretory component (SC) on deparaffinized tissue sections. Keratin was positive in 29% of well differentiated adenocarcinoma, significantly lower than in moderately or poorly differentiated adenocarcinoma. Likely, vimentin was positive in 27% of well differentiated adenocarcinoma, significantly lower than in moderately or poorly differentiated adenocarcinoma. SC was positive in 66% of well differentiated adenocarcinoma, significantly higher than in moderately or poorly differentiated adenocarcinoma. In the subtyping of well differentiated adenocarcinomas, keratin showed higher positive results in the bronchial surface epithelial, goblet cell, and bronchial gland types than in the Clara cell or type II alveolar epithelial cell type. These findings suggest that immunoperoxidase stains for keratin, vimentin, and SC may be useful for determining the degree of differentiation of adenocarcinomas of the lung as well as for subtyping of well differentiated pulmonary adenocarcinomas.