<unk>  is the lobar consolidation of the lung which has an appearance of a mass. It is usually due to bacterial infection. It is  most commonly seen in the superior segments of the lower lobes. It affects pediatric patients more than adults.
Round pneumonia
Trapped lung
Urinothorax
Hemothorax
Pulmonary aspiration
Chylothorax
Pleurisy
Parapneumonic effusion