Fig. 3

Tumor observation in the right lower lung lobectomy specimen. a Low magnification (× 0.5) imaging. A tumor with a central solid area is observed in the lung parenchyma; b (× 100 magnification). The upper left is the adenocarcinoma component, and the lower right is the squamous carcinoma component seen in the solid portion (scale bar 100 μm); c The adenocarcinoma shows a lepidic growth pattern (scale bar 50 μm). TTF-1 immunostaining is positive (inset); d (× 400 magnification) showing the squamous cell carcinoma component. Proliferation of atypical cells with acidophilic cytoplasm and intercellular bridges are observed (scale bar 20 μm)