The diagnostic utility of the triple markers Napsin A, TTF-1, and PAX8 in differentiating between primary and metastatic lung carcinomas.

Napsin A and thyroid transcription factor-1 (TTF-1) are useful biomarkers for differentiating lung adenocarcinoma from squamous cell carcinoma and also for differentiating primary lung adenocarcinoma from metastatic lung carcinoma. Pair-boxed 8 (PAX8) can help in distinguishing primary lung carcinoma from metastatic carcinomas and help to determine the primary sites of metastatic carcinomas. Immunohistochemistry for Napsin A, TTF-1, and PAX8 were performed on 193 cases of carcinoma: 50 primary lung carcinoma and 143 carcinomas from other sites.