Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: There is relative lucency at the right upper lung , corresponding to a large bulla seen on prior chest CT . Lower lung reticular opacities are consistent with clinical history / chest CT of pulmonary fibrosis . A more confluent region of opacity in the right lower lung is new , raising the possibility of superimposed infection . The heart and mediastinum are stable .
    OUTPUT:
    
Known pulmonary fibrosis , however a more focal region of airspace opacity in the right lower lung could represent infection .