Pulmonary Embolism (PE)

Epidemiology:

Common sites:

Gross features:

• coiled thrombi not conforming to shape of pulmonary arterial tree
• thrombi within lower extremity (popliteal, femoral, ileac veins)
• plethora of all tissues (congested appearance of organs and soft tissues)
• cor pulmonale, cardiovascular collapse, or sudden death may occur with 60% obstruction of pulmonary circulation
• infarction may occur with occlusion of smaller, end-arterial vessels
• may require poor left ventricular function
• wedge-shaped with occluded vessel near the apex
• hemorrhagic, raised, red-blue area
• fibrinous exudate over apposed pleural surface
• over time, colour turns red-brown, then gray-white starting at margins, then contracted scar
• post-mortem blood clot:
• gelatinous
• dark red dependent portion
• yellow “chicken fat” supernatant resembling melted and clotted chicken fat
• usually not attached to wall of vessel

Histologic features:

• platelet-fibrin-RBC mass with lines of Zahn
• if several days post-embolism, may see organization of pulmonary arterial wall
• veins may demonstrate organization
• pulmonary infarction:
• ischemic necrosis of alveolar walls, bronchioles, and vessels

Immunophenotype:

Marker:

Sensitivity:

Specificity:

Molecular features:

Other features:

• Risk factors:
• Immobilization
• Obesity
• Recent surgery
• Cancer
• Indwelling central venous line (atrial thrombus)
• MI
• DIC
• HIT
• Cardiomyopathy
• Nephrotic syndrome
• Hyperestrogenic states:
• Oral contraceptives
• Pregnancy
• Sickle cell anemia
• smoking

• hereditary predispositions:
• congenital deficiencies: antithrombin III, protein C, protein S, plasminogen
• activated protein C resistance (Factor V Leiden)
• hyperhomocysteinemia
• elevated levels of antiphospholipid antibody

References:

• Robbins 2005
• Essentials of AP (2006)