Pulmonary embolism

Pulmonary embolism, abbreviated PE, is often on the differential in autopsies, as it is not easy to diagnose clinically. Pulmonary embolism is a non-specific term; it may refer to a number of things, including:

• Pulmonary venous thromboembolism.
• Pulmonary fat embolism.
• Pulmonary foreign body embolism.
• Pulmonary septic embolism.

PE usually refers to pulmonary venous thromboembolism, abbreviated VTE, if not otherwise specified.

Clinical

• Shortness of breath (dyspnea) - classic symptom.
• Tachycardia.
• Chest pain.
• Findings associated with deep vein thrombosis
  • Leg pain.
  • Leg swelling.

Notes:

• Venous thrombosis OR~=12 for PE.

Risks factors (VTE)

• Trauma.
• Immobility.
• Pregnancy.
• Medications (e.g. OCPs).
• Hypercoagulable states (memory device CALMSHAPES):
  • Protein C deficiency.
  • Antiphospholipid antibody syndrome (APLA).
  • Leiden factor V deficiency.
  • Malignancy.
  • Protein S deficiency.
  • Homocystinemia.
  • Antithrombin deficiency.
  • Prothrombin G20210A.
  • Excess factor VIII.
  • Sticky platelet syndrome.

Gross (VTE)

Features:

• Intravascular spagetti with cream sauce.
• Leg swelling.
• Lines of Zahn.
  • Pale layers consisting of platelets and fibrin alternating with layers of RBCs; components layer during blood flow.

Notes:

• Post-mortem thrombi: one (superior) yellow portion (called "chicken fat") and one (dependent) red portion (RBCs); components layer due to gravity.

Pre- and post-mortem clots

Feature/time	Pre-mortem	Post-mortem
Shininess	dull	shiny
Adherent to wall	yes	no
Colour	grey	dark purple or bilayered red/yellow
Pressurized	yes; ejects itself	no; needs to be pulled-out
Image	micro	?

Microscopic (VTE)

Features:

• Layers consisting of platelets and fibrin alternating with layers of RBCs; Lines of Zahn.

Images:

• Lines of Zahn (utah.edu).
• Lines of Zahn (ucsf.edu).

See also

• Pulmonary pathology.