FINDINGS:
The heart is mildly enlarged.  The mediastinal and hilar contours
 appear unchanged.  There is a reticular abnormality in the right lower lung,
 particularly in the right lower lobe.  Although interstitial opacification
 appears very similar on the lateral view, opacification in the right
 cardiophrenic angle appears somewhat increased, possibly due to a worsening
 underlying interstitial process.  Other possibilities include increasing
 atelectasis associated both with an eventration of the hemidiaphragm and a
 prominent pericardial fat pad, developing bronchopneumonia is also a
 possibility.  There is no pleural effusion or pneumothorax.  Bony structures
 are unremarkable.

IMPRESSION:
Patchy right infrahilar opacity superimposed on previously seen
 interstitial lung disease.  Differential considerations for this appearance
 include worsening interstitial lung disease with or without superimposed
 developing pneumonia versus atelectasis associated with elevation of the right
 hemidiaphragm.  Correlation with clinical symptoms and laboratory data is
 recommended.  Short-term followup radiographs may be helpful to evaluate
 further if clinically indicated and if a potential source for infection is not
 otherwise identified.