FINDINGS:
Heart size is normal.  The mediastinal and hilar contours are normal. The
 pulmonary vasculature is normal.  There is a retrocardiac opacity which
 obscures the left hemidiaphragm concerning for pneumonia. There is no evidence
 of pneumothorax.  Small left pleural effusion is noted.  Large .8-cm
 (craniocaudal) left-sided pleural based lateral opacity may represent a
 loculated pleural effusion.

IMPRESSION:
Left lower lobe pneumonia with small left pleural effusion.
 
 Lateral left-sided pleural based lesion may represent a loculated pleural
 effusion. Recommend CT for further evaluation.