Pulmonary Infarction

Chest x-ray demonstrates a peripheral airspace opacity (arrows) that has a wedge-shaped configuration and a blunt medial apex pointing toward the hilum

Coronal-reformatted CT images confirm the presence of airspace opacity in the right middle lobe (arrows) with an embolus in the corresponding segmental pulmonary artery (arrowhead)

Facts: 

• Pulmonary embolic obstruction can occur with or without resultant pulmonary infarction
• In pulmonary embolism with infarction, process begins as "incomplete" infarct (intra-alveolar hemorrhage without necrosis of alveolar wall), which can go on to necrosis "infarct" especially in patients with underlying unhealthy lung
• On CXR, infarct is seen as a wedge-shaped, pleural-based consolidation with a rounded convex apex directing toward the hilum "Hampton hump"
• Often occurs in lower lobes
• Heals with scar formation

Reference

Dalen JE. Pulmonary embolism: what have we learned since Virchow? Chest 2002; 122:1440-1456.