Figure 3. Adenocarcinoma of the left upper lobe in a 66-year-old man. CT scan obtained at the level of the aortopulmonary window shows a 7-mm-diameter subaortic node (ATS station 5) (arrow), which lies lateral to a calcified ligamentum arteriosum (arrowhead). The node contained tumor tissue at thoracotomy, a finding consistent with N2 disease. * = adenocarcinoma.