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Round atelectasis (a.k.a. folded lung, Blesovsky’s syndrome) is a focal, rounded area of collapsed lung that mimics a mass, usually subpleural, and associated with pleural disease (especially asbestos-related pleural thickening or effusion). It is benign but often mistaken for neoplasm.

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Etiopathogenesis

  1. Pleural thickening and fibrosis from chronic pleural inflammation (e.g. from asbestos)
  2. Adhesion of lung to fibrotic pleura causes lung to infold upon itself
  3. Folding brings vessels and bronchi into center creating comet-tail sign on imaging

Associations:

Frequent Causes Notes
Asbestos exposure Most common association
Prior pleural effusion Tuberculosis, uremia, lupus, hemothorax
Pleural thickening Regardless of cause (e.g., post-traumatic)
Post-radiation fibrosis Less common

Typical Location

Radiology

Chest X-Ray

Findings Description
Round or oval opacity near pleura Usually basal and peripheral
Adjacent pleural thickening May be subtle or obvious
Mimics lung mass Requires CT for further characterization

CT Chest (Modality of Choice)

Characteristic Feature Description
Comet-tail sign Curved bronchovascular structures converging to lesion (PATHOGNOMIC)
Pleural thickening In continuity with mass
Rounded, subpleural mass Often <4 cm; adjacent volume loss may be seen
No mass effect or vascular encasement Differentiates from malignancy
“Crow’s foot” sign Alternate term for radiating vessels/bronchi

Differentials

Entity Key Differentiator
Peripheral lung cancer No comet-tail sign; may show mass effect, irregular enhancement
Pulmonary infarct Wedge-shaped, often with pleural effusion
Rounded pneumonia Febrile illness; responds to antibiotics
Pleural metastasis Multiple nodules; no converging vessels
Pulmonary hamartoma May contain fat or popcorn calcification