Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: The patient 's neck is flexed and the head obscures the left apical region . There is slightly reduced lung volumes as compared to prior . There is stable cardiomegaly with left ventricular prominence . There has been increase in the left retrocardiac opacity most likely representing pleural effusion ; however , in the appropriate clinical setting , superimposed pneumonia must be considered as well . There is no evidence of vascular congestion or pulmonary edema . The right hilum appears fuller than it had on the prior ; however , direct comparison can not be made given the differences in technique . Pleural surfaces are unremarkable . There is no pneumothorax .
    OUTPUT:
    
Increasing left lower lung field opacity most likely representing pleural effusion ; however , in the appropriate clinical setting , superimposed pneumonia must be considered .