General Considerations

• Most thoracic trauma is due to motor vehicle accidents
• Most thoracic trauma is blunt, rather than penetrating
• Lacerations usually result from blunt chest trauma
• They represent tears in the lung parenchyma
• Lacerations filled with air are called pneumatoceles, and those filled with blood are called pulmonary hematomas
• They tend to occur more often in children and young adults

Clinical Findings

• No symptoms from laceration itself unless it becomes infected,
  which is rare

Imaging Findings

• Usually not apparent at first because of surrounding pulmonary
  contusion
• Contusions characteristically clear rapidly, sometimes within
  48 hours
• On CT, they will present as cystic lucencies, frequently beneath a rib fracture
• CT is more sensitive than conventional radiographs for detecting a pulmonary laceration
• Half are solid, mass-like lesions (pulmonary hematoma)

Pulmonary Hematoma. Following blunt chest trauma on the left, a small, solid-appearing, soft tissue nodule appeared in the lingula (red arrows) representing pulmonary laceration filled with blood.

• Half are thin-walled cystic structures (traumatic lung cyst
  or pneumatoceles) with or without air-fluid level — depends on
  how much bleeding into laceration
• Usually subpleural location under point of maximum impact
• May be single or multiple

Treatment

• Supportive: oxygen, assisted ventilation if needed

Prognosis

• Characteristically, they take a long time to heal – weeks to months
• Gradually decrease in size