Napsin A, a New Marker for Lung Adenocarcinoma, Is Complementary and More Sensitive and Specific Than Thyroid Transcription Factor 1 in the Differential Diagnosis of Primary Pulmonary Carcinoma: Evaluation of 1674 Cases by Tissue Microarray

Nap-A is superior to TTF-1 in distinguishing primary lung ACA from other carcinomas (except kidney), particularly primary lung small cell carcinoma, and primary thyroid carcinoma. A combination of Nap-A and TTF-1 is useful in the distinction of primary lung ACA (Nap-A(+), TTF-1(+)) from primary lung squamous cell carcinoma (Nap-A(-), TTF-1(-)) and primary lung small cell carcinoma (Nap-A(-), TTF-1(+)).