Fleichner's Sign

One of the classic plain CXR film signs of pulmonary thromboembolism.
 
CXR finding: In severe or bulky central pulmonary embolism, the central pulmonary artery will be filled with clot and appear expansive or enlarged on the plain CXR.

Common Associated Finding:  Westermark's Sign is another classic plain film CXR sign of pulmonary embolism appearing as an abrupt cut off and attenuation of the pulmonary arterial branches at the site of the thrombus.

Radiologic Clues: This sign is extremely non-specific and generally impossible to quantify and should only be seriously considered in an appropriate clinical background.

"Aunt Sophies":  Most often prominent but normal central pulmonary arteries, hilar masses or adenopathy, pulmonary arterial hypertension.