Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Single frontal view of the chest . Heart size and mediastinal contours are normal . Medial right lung base and retrocardiac opacities are new and consistent with multifocal pneumonia . A spiculated nodule in the left upper lobe is similar to prior . Other known nodules were better evaluated on prior CT . Indistinct appearance of the left hemidiaphragm suggests the presence of a small pleural effusion . No pneumothorax .
    OUTPUT:
    
Symmetric right base and retrocardiac opacities may represent either atelectasis or pneumonia .