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Left lower lobe collapse

Case contributed by Dr Derek Smith


Cough and desaturations on background of recent left lower lobe pneumonia and COPD.

Patient Data

Age: 80
Gender: Male

Airspace opacification in the left lower zone, with loss of definition of the medial left hemidiaphragm. With this, a straight border is seen going from the diaphragm to the AP window. This is known as the "sail sign" and demonstrates left lower lobe collapse.

Case Discussion

Sail sign is a descriptive term for left lower lobe collapse. As the tissues lose aeration, the density of the lobe increases and collapses medially.

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