Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Heart size is normal with trace unfolding of the thoracic aortic arch . Cardiomediastinal silhouette and hilar contours are normal . Questionable 3 cm ovoid density in the left lung base with possible retrocardiac correlate . Lungs are otherwise clear . Pleural surfaces are clear without effusion or pneumothorax . Bones are diffusely demineralized .
    OUTPUT:
    
Indeterminate 3 cm ovoid density in the left lung base with possible retrocardiac correlate on lateral view . While it is possible this represents a nipple shadow , either repeat radiograph with nipple markers or CT examination is recommended .