Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Frontal and lateral chest radiographs demonstrate a normal cardiomediastinal silhouette and fairly well - aerated lungs . There is a retrocardiac opacity adjacent to the left hemidiaphragm , better seen on lateral view . This could represent an early developing pneumonia . No appreciable pleural effusion or pneumothorax is seen . The visualized upper abdomen is unremarkable .
    OUTPUT:
    
Retrocardiac opacity adjacent to the left hemidiaphragm , better seen on lateral view . This could represent an early developing pneumonia in the appropriate clinical setting .