The CXR shows a focal shadow in the right lower lobe with air bronchograms suggestive
of pneumonia. It is clearly in the right lower lobe because the right hemidiaphragm is effaced. Right middle lobe
shadows would efface the right heart border. The presence of air bronchograms indicates pathology in the alveoli,
as the conducting airways remain patent with air. Water or blood can also occupy the alveoli as a result of
pulmonary edema or pulmonary hemorrhage respectively. There should be other supporting signs such as
cardiomegaly, upper lobe diversion, and Kerley B lines with pulmonary edema. The differential diagnoses of a
focal shadow with air bronchograms include bronchoalveolar cell carcinoma and lymphoma. It
is important to follow-up the CXR to ensure that total resolution of infection occurs. This may take up to three
months in the elderly but generally some improvement usually occurs within a week. The borders of the heart on a
PA CXR SVC – superior vena cava, RA – right atrium, Ao – aortic knuckle, LA – left atrium, LV – left ventricle