(a) Chest CT showing the mass opacity of the diameter 55 × 45 mm in size in the left upper lobe. Severe emphysema is visible in the background. (b) Pathology (hematoxylin and eosin staining, 400x) shows a part of carcinoma with slit-formed duct formation of carcinoma and immature mesenchymal cells. (c) Vimentin (100x) is diffusely positive for the mesenchymal cells. (d) TTF-1 (100x) is positive in parts of carcinoma with the slit-formed duct formation.