Rapid multiplex immunohistochemistry using the 4-antibody cocktail YANA-4 in differentiating primary adenocarcinoma from squamous cell carcinoma of the lung.

The current Food and Drug Administration-approved standard treatment for non-small cell carcinomas consists of carboplatin/taxol/avastin. However, nowadays more specialized protocols, depending on tumor subtype, are being used for lung cancer patients. Therefore, accurate differentiation between adenocarcinoma and squamous cell carcinoma is essential for the selection of appropriate therapies. We designed a rapid multiplex immunostaining method using a novel 4-antibody cocktail, YANA-4. This antibody cocktail consists of the following monoclonal antibodies: rabbit for thyroid transcription factor 1(TTF-1), mouse for napsin A, mouse l for p63, and rabbit for CK14. All procedures can be completed within 3 hours. This method labels the nuclei of adenocarcinomas as brown with TTF-1, and cytoplasm as blue with napsin A. Squamous cell carcinomas could be differentiated from adenocarcinomas with an inverse staining pattern: blue nuclei with p63 and brown cytoplasm with CK14. In this study, 97.4% (38 of 39) of adenocarcinomas showed brown nuclei (TTF-1) and/or blue cytoplasm (napsin A), with 4 cases showing positivity only for brown nuclei (TTF-1) and 1 case only for blue cytoplasm (napsin A). None of the squamous cell carcinoma cases showed these staining patterns. Positivity for blue nuclei (p63) and/or brown cytoplasm (CK14) was detected in 100% (25 of 25) of squamous cell carcinomas, with 1 case showing positivity only for brown cytoplasm (CK14) and 2 cases only for blue nuclei (p63). None of the adenocarcinoma cases showed these patterns. This rapid immunohistochemical method can thus be considered highly specific and sensitive for differentiating adenocarcinomas and squamous cell carcinomas.