Interstitial lung markings on CXR DDx

Overview

Increased interstitial markings seen on chest x-ray may also be referred to as a fine reticular pattern

Features

Peribronchovascular connective tissue thickening

• Peribronchial cuffing (bronchus on-end)
• “Tram tracks” (side view of bronchus)
• Blurred vascular markings (indistinct margins)

Septal connective tissue thickening

• Thickened interlobular septa (called Kerley B or septal lines)
• Fine reticular pattern (Kerley C lines = superimposed Kerley B lines)
• Kerley A lines (thickened deep intraparenchymal septal bands that radiate from the hilum in the upper lungs)
• Thickened interlobar fissures (subpleural connective tissue thickening)

 Causes

Acute—often associated with airspace filling

• 
Interstitial pulmonary edema
• 
Interstitial pneumonitis — viral, mycoplasma

Chronic interstitial lung diseases

• Neoplastic infiltration (lymphangitic carcinomatosis, lymphoma)
• Sarcoidosis
• Collagen-vascular diseases
Interstitial pneumonitis
• Idiopathic pulmonary fibrosis
• Pneumoconiosis (silicosis, asbestosis)