Lung contusion and laceration are injuries to the lung. In contusion, the structure of the lung does not change. In laceration, the pieces of lung may be moved. When blood fills lacerations, the injury is called pulmonary hematoma. The difference between a contusion and a hematoma is that in a contusion, the alveoli (tiny air-filled sacs that give oxygen) will bleed, but a hematoma is a blood clot.