Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: The cardiac and mediastinal contours appear unchanged . There is persistent collapse of the right upper lobe . A moderate - to - large pleural effusion has substantially decreased in size . There is no definite pneumothorax . The left lung remains clear .
    OUTPUT:
    
No evidence of pneumothorax . Substantial decrease in right - sided pleural effusion . Persistent right upper lobe collapse worrisome for post-obstructive pneumonitis . The possibility of underlying central malignancy to explain this appearance should be considered .