Expression of vimentin in surgically resected adenocarcinomas and large cell carcinomas of lung

The expression of vimentin in pulmonary carcinomas was studied in 285 cases of surgically resected lung cancer from our hospital files. Formalin fixed, paraffin-embedded sections were studied by immunoreactive staining techniques using two monoclonal antibodies against vimentin. Cases demonstrating vimentin positivity by the avidin-biotin-peroxidase method included 11 of 129 adenocarcinomas studied (8.5%), and 15 of 61 large cell carcinomas studied (24.6%). Vimentin expression was not seen in any of the 51 squamous cell carcinomas or 35 small cell carcinomas in our series. The positive cases of adenocarcinoma were in moderately and poorly differentiated cancers. Four of the eight giant cell carcinomas (50%) demonstrated vimentin expression. All cases that exhibited vimentin positivity were studied for cytokeratin expression. Coexpression of vimentin and cytokeratin was demonstrated not only within the same tumor but also within the same cells in some cases stained by double antibody technique, including both adenocarcinomas and large cell carcinomas. Similar immunoreactive methods were also applied to sections from human lung cancer transplants grown in the nude mouse. Of 28 tumors studied, four of 11 adenocarcinomas (36%) and all 4 large cell carcinomas demonstrated coexpression of vimentin and cytokeratin, while none of the five squamous cell carcinomas or eight small cell carcinomas expressed vimentin.