Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Frontal and lateral views of chest were obtained . Dual - lead left - sided pacemaker is again seen with leads extending to the expected positions of the right atrium and right ventricle . Left perihilar opacity is again seen , grossly similar in appearance , consistent with known mass and parenchymal scarring . There is persistent blunting of the left costophrenic angle which appears slightly increased since the prior study . Left retrocardiac opacity may relate to combination of effusion and atelectasis , however underlying consolidation can not be excluded . The right lung is clear .
    OUTPUT:
    
1 . Left pleural effusion which appears increased since the prior study . Left retrocardiac opacity may relate to combination of effusion and atelectasis , however underlying consolidation can not be excluded . 2 . Left perihilar opacity consistent with known mass and parenchymal scarring . Grossly stable appearance of the left perihilar region .