|TTF-1 + Napsin A
||TTF-1 + Napsin A
||Napsin A is an aspartic pertinase involved in the maturation of surfactant protein B. It is detected in the cytoplasm of type II pneumocyte and alveolar macrophages and is a very sensitive and specific marker for lung adenocarcinomas. Studies have show that when TTF-1 (nuclear stain, brown color) and Napsin A (cytoplasm, red color) are used in combination, a higher sensitivity and specificity is achieved to identify the adenocarcinoma of lung primary.