Knuckle sign - pulmonary embolism

Case contributed by Dr Liz Silverstone


Acute dyspnea. Recent long-haul flight.

Patient Data

Age: 90 years
Gender: Female

Disproportionately large right lower lobe pulmonary artery.

Multiple pulmonary emboli with right lower lobe predominance.

Hiatal hernia is also noted.

Case Discussion

Abrupt tapering of a major pulmonary artery is a rare chest x-ray sign of pulmonary embolism, and is known as the knuckle sign.

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