A<unk>  is a substance denser than air, such as pus, blood, or protein, which lingers within the parenchyma of the lungs.<unk> s are associated with pneumonia, tuberculosis, and sarcoidosis.<unk> s can be observed on a chest radiograph.
Pulmonary infiltrate
Pulmonary consolidation
Parapneumonic effusion
Pleurisy
Pleural effusion
Hydrothorax
Subcutaneous emphysema
Lung nodule