Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Heart size is top normal . Calcifications of the aortic knob are noted . There are small bilateral pleural effusions with adjacent atelectasis . The lungs are well expanded . A round opacity is noted at the left base medially , which may reflect atelectasis , calcifications , or a mass .
    OUTPUT:
    
Round opacity at the left base , which may represent a mass . Chest CT is recommended for further evaluation . Small bilateral pleural effusions with atelectasis .