Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: PA and lateral chest radiographs demonstrate diffuse interstitial opacities involving much of the left mid and upper lung . There is no hilar lymphadenopathy , pleural effusion or pneumothorax . The heart size is normal .
    OUTPUT:
    
Left lung interstitial opacities of unknown age . In a patient with a history of positive PPD and recent respiratory symptoms , primary tuberculosis can not be excluded . Lymphangitic carcinomatosis is also possible as well . Further evaluation with chest CT is recommended . The case was discussed by Dr . ___ with Dr . ___ by phone at 10 :56 a .m . on ___ . Findings were initially discussed with Dr . ___ by phone at 10 :34 a .m .