Anterior bronchus sign

Dr Henry Knipe and Assoc Prof Frank Gaillard et al.

The anterior bronchus sign refers to the appearance of the anterior segmental bronchus of the upper lobes as seen on a frontal chest radiograph.

Gross anatomy

The anterior segment bronchus of the upper lobes courses anteriorly and laterally. When the orientation is predominantly anteriorly the bronchus is seen end-on as a ring shadow. This occurs ~50% of the time.

Related pathology

The upper limit of the adjacent soft tissue thickness:

  • normal: <3 mm of soft tissue lateral to the bronchus
  • abnormal: >6 mm of soft tissue implies the presences of a mass, and warrants cross-sectional imaging
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Article information

rID: 8833
System: Chest
Section: Signs
Synonyms or Alternate Spellings:

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Cases and figures

  • Normal anterior b...
    Case 1: normal anterior bronchus shadows
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