Figure 5d. Radiologic findings in a 67-year-old man with moderately differentiated squamous cell carcinoma. (a) Posteroanterior radiograph shows a mass (*) overlapping aspects of the left hilum. (b) Lateral radiograph shows a homogeneous area of increased opacity (*) within the superior segment of the left lower lobe. Cutoff of the superior segmental bronchus (arrow) suggests that much of the area of increased opacity could represent postobstructive pneumonia. (c) CT image obtained at the level of the left pulmonary artery shows the mass with regions of necrosis within it (*). The anterior aspect of the lesion appears to invade the mediastinum posterior to the artery (arrowheads). (d) CT image obtained at the level of the right pulmonary artery shows involvement of the posterior left hilum with cutoff of the superior segmental bronchus (arrowhead) and subcarinal lymphadenopathy (arrow). It is difficult to distinguish necrosis within the mass from necrosis within postobstructive pneumonia. (e) CT image obtained after RT shows stabilized sequelae of the therapy. Note the volume loss in the region of the original mass with associated radiation bronchiectasis (arrowheads).