A<unk>  is a region of normally compressible lung tissue that has filled with liquid instead of air. The condition is marked by induration (swelling or hardening of normally soft tissue) of a normally aerated lung. It is considered a radiologic sign.<unk>  occurs through accumulation of inflammatory cellular exudate in the alveoli and adjoining ducts. The liquid can be<unk>  edema, inflammatory exudate, pus, inhaled water, or blood (from bronchial tree or hemorrhage from a<unk>  artery).<unk>  must be present to diagnose pneumonia: the signs of lobar pneumonia are characteristic and clinically referred to as<unk> .
Pulmonary consolidation
Pulmonary infiltrate
Parapneumonic effusion
Focal lung pneumatosis
Lung nodule
Pleural effusion
Pleurisy
Malignant pleural effusion