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Westermark's Sign
Pathophysiology: Seen in pulmonary thromboembolic disease
with a large embolism in the main or major branch of a pulmonary
artery. There is an abrupt cutoff of vascular branching and
regional hyperlucency in an area subtended by the occluded
vessel.
Clinical/Radiologic Clues: Classic radiologic sign rarely
seen on plain films and not usually helpful in diagnosis.
Historical context: one of the many “honor” signs for great
radiologists: e.g. Fleichner’s sign, Rigler’s sign,
etc…
CXR Findings:
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Classic:
abrupt cutoff of main or large pulmonary artery branch with
oligemia and hyperlucency in subtended lung **
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Fleischner’s
sign: fullness of the pulmonary artery filled with clot,
also rare
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May be associated
with any other findings seen in PE (see Pulmonary Embolism)
“Aunt Sophies”: gamut of regional area of lung oligemia
and hyperlucency
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Tumor: compression
or encroachment of pulmonary artery or major branch and
regional oligemia
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Rarely sarcoma of a
pulmonary artery or branch
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Vasculitis of major
pulmonary vessel(s)
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Regional emphysema,
bullous emphysema, or air trapping
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Regional air
trapping: bronchostenosis (e.g. TB), bronchiectasis (e.g.
cystic fibrosis), asthma with mucus plugging
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Rarely hypoxic
states with pulmonary arterial constriction
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