A 58-year-old woman presents to the emergency department with acute onset dyspnea and right-sided pleuritic chest pain. She had undergone total abdominal hysterectomy 5 days ago. Vital signs: BP 118/76 mmHg, HR 102/min, RR 22/min, SpO₂ 94% on room air. D-dimer is elevated at 2.8 μg/mL. CT pulmonary angiography (CTPA) is performed. The radiologist reports a filling defect within the right lower lobe segmental pulmonary artery with acute thrombus. The right lower lobe shows wedge-shaped peripheral consolidation. What is the most specific radiological sign demonstrated in this patient?

Explanation

## Radiological Signs of Pulmonary Embolism on CTPA **Key Point:** Hampton's hump is a wedge-shaped peripheral consolidation (infarct) that occurs when PE causes pulmonary infarction, typically in the lower lobes due to dual blood supply compromise. ### Hampton's Hump — Definition & Mechanism 1. Wedge-shaped opacity with base on pleura 2. Occurs in ~10% of PE cases (requires pulmonary infarction) 3. Results from hemorrhagic infarction when embolic occlusion + compromised bronchial circulation 4. Most common in lower lobes (gravity-dependent) 5. Can appear within hours to days post-PE ### Other CTPA Signs — Differential | Sign | Appearance | Mechanism | Frequency | |------|-----------|-----------|----------| | **Hampton's hump** | Wedge-shaped peripheral consolidation | Pulmonary infarction | ~10% | | **Westermark sign** | Abrupt vascular cutoff + distal oligemia | Proximal PE with vessel occlusion | ~5–10% (CXR, rarely on CTPA) | | **McConnell sign** | RV dilatation + normal RV apex | Acute RV strain | ~20–30% on CTPA | | **Knuckle sign** | Abrupt vessel termination | Embolic occlusion | Variable | **Clinical Pearl:** Hampton's hump is the MOST SPECIFIC sign for PE because it indicates actual pulmonary infarction, not just vessel occlusion. However, it is uncommon (~10%) because most PE do not cause infarction (dual blood supply protects most lung). **High-Yield:** On CTPA, the direct sign of PE is the **filling defect** (thrombus within vessel). Hampton's hump is an indirect sign (consequence of infarction). The combination of filling defect + wedge-shaped consolidation = Hampton's hump. ### Why This Patient? - Recent surgery → immobility + hypercoagulability - Acute PE with lower lobe segmental artery occlusion - Wedge-shaped peripheral consolidation = infarction - This is Hampton's hump [cite:Harrison 21e Ch 297]