Diagnostic Value of Immunohistochemistry Panel of P63, CK5/6, TTF1, NapsinA in the Diagnosis of Adenocarcinoma and Squamous Cell Carcinoma of Lung

Background: Lung cancer is one of the most frequently diagnosed malignant neoplasms in the world. The pulmonary carcinomas are divided into two major categories, namely small cell lung carcinoma (SCLC) and non-small cell lung carcinoma (NSCLC).Traditionally, the treatment for NSCLC was based on tumor stage, irrespective of histologic subtypes; over the recent years, however, with the development of targeted therapies with different adverse or therapeutic effects on each subtype, it is crucial to correctly subcategorize NSCLC. Utilizing Immunohistochemical (IHC) markers may be conducive to obtain this objective, yet no single marker is sensitive or specific enough to differentiate SCC and adenocarcinoma. Therefore, in the present research, we want to use a panel consisting of P63, CK 5/6, TTF-1, and Napsin A. Methods: 83 cases of NSCLC (36 adenocarcinoma, 37 squamous cell carcinoma and 10 poorly differentiated carcinoma) were selected. IHC examination for P63, TTF-1, Napsin A, and CK 5/6 were performed on tissue sections obtained from formalin-fixed, paraffin embedded blocks. Results: TTF1 had 94% sensitivity and 69% specificity with PPV 73% and NPV 92%, and NaspsinA had 91% sensitivity and 97% specificity with PPV 97% and NPV 92% as regards the diagnosis of adenocarcinoma. P63 had 100% sensitivity and 84% specificity with PPV 87% and NPV 100%, and CK5/6 had 100% sensitivity and 69% specificity with PPV 78% and NPV 100% in the diagnosis of squamous cell carcinoma. Conclusion: Using an IHC panel of TTF-1, Napsin A, P63, and CK5/6 it is possible to reliably diagnose poorly differentiated NSCLC with no evident glandular or squamous differentiation.