Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Cardiomediastinal contours are within normal limits . Lungs are grossly clear except for a smoothly marginated 1 .6 cm diameter opacity overlying the right fourth anterior rib , very likely due to a nipple shadow . As a lateral radiograph was not obtained , and as in this appears asymmetrical compared to the left side , a repeat radiograph with nipple markers is suggested to confirm this is a nipple and not a lung nodule .
    OUTPUT:
    
No evidence of pneumonia . Repeat radiograph with nipple markers is recommended to confirm a presumed nipple shadow on the right as described above .