Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: The heart is normal in size . The mediastinal and hilar contours appear within normal limits . There is no pleural effusion or pneumothorax . There is a nodular focus measuring up to 11 mm which projects along the left lower lung , possibly a nipple shadow but potentially a true pulmonary nodule of substantial size . Otherwise , the lungs appear clear . Bony structures are unremarkable .
    OUTPUT:
    
Nodular focus projecting over the left lower lung , possibly a nipple shadow . When clinically appropriate , a repeat PA view with nipple markers is recommended to assess further . A true pulmonary nodule of substantial size is an additional possibility , however , which should be excluded .