Focal lucencies in the thorax and Cavities

If you see focal lucency, you should see the wall of the lesion-

If you see focal lucency, you should see the wall of the lesion-

  1. If the wall of the lesion is just perceptible, or of hairline thickness, and the lesion is more than 1 cm in size, it is a  Bulla.
  2. If the wall of the lesion perceptible and more than 3 mm in thickness it is a  Cavity.
  3. If there is fluid in the cavity, or if there is the presence of air-fluid level, it is an  Abscess formation or Hemorrhage, within the cavity.
  4. If there is a thin walled cavity in the hilar region, in a child with pneumonia, it is a  Pneumatocele.

Cavity in left middle zone ( note wall thickness more than 3 mm).


Note apical bulla in left upper lobe. Note the thin , just barely perceptible wall

When you see a cavity, you should try to differentiate a benign cavity from malignant cavity.

Benign Cavity

Malignant cavity

Has thin to intermediate thick wall ( less than 15 mm thickness)

Wall is thicker than 15 mm.

Has regular inner margins

Inner margin is nodular and thickened

Usually associated consolidation/ alveolar opacities

No similar associations.


Note the irregular, thick walled cavity, malignant cavitory lesion.


Note the intermediate wall thick cavity in right upper lobe. Inner margins of cavity are smooth . This is a benign cavity. A Case of tuberculosis.



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