Anterior junction line

Dr Henry Knipe et al.

The anterior junction (junctional) line is a feature of frontal chest x-rays and chest CTs. It is a result of the parietal and visceral pleura meeting anteromedially. It normally contains a small amount of fat but can form a stripe of variable thickness if there is a lot of fat present or by the presence of the thymus in young patients 1.

Anterior mediastinal masses can cause obliteration of the anterior junction line 3

Occasionally the anterior junction line may mimic pneumomediastinum, so called pseudopneumomediastinum.

Radiological appearance

Plain radiograph
  • seen on ~40% (range 25-57%) of frontal chest x-rays 1
  • oblique course crossing the upper two-thirds of the sternum from the upper right to lower left 1, 2 and does not extend above the manubriosternal joint 3
CT
  • seen as a thin, dense line separating the two lungs in anterosuperior portion of the chest 2

Chest x-ray
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Article Information

rID: 22119
System: Chest
Section: Anatomy
Synonyms or Alternate Spellings:
  • Anterior junctional line

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Cases and Figures

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    Case 1: anterior and posterior junctional lines
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    Case 1: blue line represents anterior junctional line
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