Elementary Lesions

Interlobular septal thickening

Characteristics

• Thin linear opacities between lobules

• Length of lines: 10 - 20 mm

• Preferential location: subpleural

• Presentation: simple lines / polygons

Diagnostic Orientation 

• If the septal lines are regular (not specific)

  • Pulmonary oedema, lymphangitic carcinomatosis, venoocclusive disease, overload diseases (such as Niemann Pick disease), Erdheim-Chester disease (ECD), acute eosinophilic pneumonia

• If the septal lines are nodular 

  • Sarcoidosis, lymphangitic carcinomatosis, lymphoma, Kaposi sarcoma

• If the septal lines are within architectural distortion

  • Sarcoidosis, lymphangitic carcinomatosis, lymphoma, Kaposi sarcoma