## Radiological Signs of Pulmonary Embolism on CT **Key Point:** Hampton's hump is a wedge-shaped peripheral consolidation with a central lucency (representing pulmonary infarction), classically seen in PE with pulmonary infarction. ### Hampton's Hump The description in the vignette — "wedge-shaped peripheral consolidation in the right lower lobe with a central lucency" — is pathognomonic for Hampton's hump. - **Definition:** Wedge-shaped area of consolidation with a central lucent zone (representing necrotic lung tissue surrounded by haemorrhage). - **Mechanism:** Occurs when PE causes pulmonary infarction, typically in the lower lobes due to gravitational dependency and dual blood supply compromise. - **Frequency:** Seen in ~10% of PE cases; indicates infarction and is associated with worse prognosis. - **Timing:** Usually appears 24–72 hours after the embolic event. **High-Yield:** Hampton's hump is a **secondary sign** of PE — it indicates infarction has occurred, not just vascular occlusion. ### Other PE Signs on CTPA | Sign | Appearance | Significance | |------|-----------|-------------| | **Westermark sign** | Abrupt cut-off of pulmonary artery; distal oligaemia | Primary sign; indicates vascular occlusion | | **McConnell sign** | RV dilatation with sparing of RV apex | RV strain; indicates haemodynamically significant PE | | **Fleischner lines** | Horizontal linear opacities in lung bases | Atelectasis; non-specific | **Clinical Pearl:** The presence of Hampton's hump in the clinical context of recent surgery (immobility risk factor) and elevated D-dimer makes PE with infarction the most likely diagnosis. **Tip:** Remember that Hampton's hump is a **late sign** (24–72 hours post-PE) and represents **tissue death**, not just vascular occlusion. It indicates a more severe, established PE. 
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