Radiopaedia.org

There is a large bulky right infrahilar mass of slightly heterogeneous enhancing soft tissue attenuation, causing obstructive atelectasis of the anterior and lateral basal segments of the right lower lobe. The mass measures 88mm AP x 85mm transverse x 97mm vertical diameter. No cavitation or calcification. No air bronchograms are visible within the mass. It appears there is a central hilar and infrahilar mass, of mixed slightly higher and lower attenuation with a possible necrotic component inferolaterally. At the superior aspect of the mass there is narrowing and abrupt obstruction of the right lower lobe bronchus and its segmental branches. There is extrinsic displacement of the right pulmonary veins, with a possible filling defect in the right inferior pulmonary vein. There is also extrinsic narrowing of the right interlobar pulmonary artery, by the adjacent infrahilar mass. At the posterior aspect of the mass, there is displacement of the atelectatic medial and posterior basal segments of the right lower lobe, which enhance slightly more than the central infrahilar mass. Ipsilateral right hilar lymph nodes are enlarged. No mediastinal or contralateral lymph node enlargement. No supraclavicular or upper abdominal lymphadenopathy. No pleural or pericardial effusion. Normal contralateral left lung and pleura. No destructive bony thoracic lesion. No abnormality of the imaged upper abdomen.

Summary:
A large central neoplastic mass causing distal obstructive atelectasis of the lateral and anterior basal segments of the right lower lobe.