Carbonic anhydrase IX is expressed in mesothelioma and metastatic clear cell renal cell carcinoma of the lung.

High immunohistochemical expression of carbonic anhydrase IX (CAIX) is found in clear cell renal cell carcinoma (ccRCC), but no studies have assessed CAIX in metastatic ccRCC (mccRCC) of the lung. As 75% of patients with mccRCC show lung involvement, characterization of protein expression in these lesions is warranted. This investigation analyzed CAIX immunohistochemical expression in pulmonary/pleural tumors including mccRCC (n = 22), mesothelioma (n = 19), squamous cell carcinoma (n = 27), small cell carcinoma (n = 9), and adenocarcinoma (n = 49), as well as other mesothelial lesions (n = 4).