Figure 9a. T1 N2 adenocarcinoma in a 40-year-old man. (a) Transaxial thin-section (1-mm collimation) CT scan (lung window) obtained at the level of the azygos arch shows a 25-mm nodule with a lobulated and spiculated margin in the anterior segment of the right upper lobe. Mediastinoscopy revealed microscopic lymph node metastases in the right lower paratracheal nodes. (b) Low-power photomicrograph (original magnification, x4; H-E stain) of a surgical specimen shows spiculated adenocarcinoma with bronchovascular invasion (arrows).