Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: There is a well - circumscribed round opacity overlying the left heart border , which is not seen on the lateral view and may represent a nipple shadow . The lungs are otherwise clear . There is no pneumothorax or pleural effusion . Hilar and cardiomediastinal contours are normal . Osseous structures are unremarkable .
    OUTPUT:
    
1 . No evidence of pneumonia . 2 . Ovoid density overlying the left cardiac border , seen only on the PA view , likely a nipple shadow . Repeat films with nipple markers may be obtained for further characterization .