Apical pleural cap

Apical pleural cap refers to a curved density at the lung apex seen on chest radiograph.

Epidemiology

The frequency of apical pleural thickening increases with age ³.

Pathology

It arises from a number of causes:

• pleural thickening/scarring
  • idiopathic: chronic ischemic etiology is favored for most cases ⁴
  • secondary to previous apical infection: typically pulmonary tuberculosis
  • radiation fibrosis
  • pleuroparenchymal fibroelastosis
  • may be present in up to 10% of radiographs ²
• Pancoast tumor
• hematoma
  • thoracic aortic injury ⁵
  • upper thoracic spine injury
  • fractured 1^st rib
• lymphoma: extending from neck/mediastinum
• abscess within the neck/mediastinum