label: Pulmonary pneumatocele
label_lc: pulmonary pneumatocele
description: "A pneumatocele is a thin walled, gas-filled space in the lung. It is most frequently caused by acute pneumonia, trauma, or aspiration of hydrocarbon fluid and is usually transient. The mechanism is believed to be a combination of parenchymal necrosis and check-valve airway obstruction. A pneumatocele appears as an approximately round, thin-walled airspace in the lung."