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Rounded Atelectasis


  • Occurs as a consequence of diseases with chronic pleural scarring, especially asbestos-related pleural disease and TB
  • Most often at the lung bases, posteromedially
  • Must be subpleural in position


  • A rapidly forming pleural effusion produces an adjacent area of passive atelectasis
  • A groove of visceral pleura may infold into the area of atelectasis and come to surround a part of it
  • If the effusion recedes at once, the lung will probably re-expand
  • If fibrinous adhesions form or if there is preexistent chronic pleural disease, then the atelectatic area of lung remains trapped by the enfolded visceral pleura
  • Asymptomatic: important because it resembles a bronchogenic ca

Imaging Findings 

  • Rounded density at lung base
  • Contiguous to area of pleural disease or superimposed on apparent asbestos-related pleural disease or TB
  • Comet tail on CT: vessels and bronchi converge upon and appear to swirl around mass
  • Crow’s feet — linear bands radiating from mass into lung parenchyma
  • Linear densities radiate back toward hilum
  • May have air bronchogram


Axial enhanced CT scan of the chest shows a nodular-area of increased density (blue arrow),
associated with pleural thickening and pleural plaques (yellow arrows) consistent with asbestos-
related pleural disease. Red arrow point to "comet tail" density that surrounds rounded atelectasis.

For a version of this photo without the arrows, click here