Other nonneoplastic disease


Last author update: 1 December 2011
Last staff update: 9 August 2020

Copyright: 2003-2023,, Inc.

PubMed search: round atelectasis [title] OR rounded atelectasis [title]

Elliot Weisenberg, M.D.
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Cite this page: Weisenberg E. Atelectasis. website. Accessed September 29th, 2023.
Definition / general
  • Incomplete expansion of lung or collapse of previously inflated lung, due to obstruction / resorption, compression or contraction
  • Obstruction: resorption of oxygen causes collapse and mediastinal shifts towards affected lung; due to mucus plugs, asthma, chronic bronchitis, bronchiectasis, postoperative changes, foreign bodies, but not usually due to tumors, which cause only subtotal obstruction
  • Compression: due to fluid (congestive heart failure), air (pneumothorax), tumor and blood; causes mediastinal shifts away from affected lung
  • Contraction: due to fibrosis (restrictive lung disease)
  • Patchy: due to loss of surfactant in acute respiratory distress syndrome
  • Rounded: Localized area of subpleural lung collapse with associated pleural fibrosis; patients usually asymptomatic with occupational exposure to asbestos; usually posterior portion of a lower lobe
Gross description
  • Rounded: lung shows ill defined atelectasis with deeply invaginated pleural folds, which may disappear during grossing
Microscopic (histologic) description
  • Rounded: pleural fibrosis and invagination (use elastic stains to highlight) and atelectasis
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