The Common Vein

• Definition:
  • Refers to any fibrosis (scarring) occurring within the lung tissue, en
    • interstitial spaces and potentially
    • other lung components such as the
      • alveoli or
      • pleura
      • airways
      • blood vessels
  • It is a broader term that includes all causes of lung fibrosis, not just interstitial involvement.
• Examples:
  • Idiopathic Pulmonary Fibrosis (IPF).
  • Post-radiation fibro
    • severe pneumonia or
    • Acute Respiratory Distress Syndrome (ARDS).

2. Interstitial Fibrosis:

• Definition:
  • Refers specifically to fibrosis confined to the interstitial tissue of the lungs, the framework supporting the alveoli and capillaries.
  • Represents a subset of pulmonary fibrosis.
• Scope:
  • Focuses on the structural connective tissue within the lung that surrounds the alveoli, excluding the pleura or airways.
• Examples:
  • Interstitial lung disease (ILD) subtypes:
    • Nonspecific Interstitial Pneumonia (NSIP).
    • Connective tissue disease-associated interstitial fibrosis.
    • Asbestosis or chronic hypersensitivity pneumonitis.

Radiological Presentation:

• Pulmonary Fibrosis:
  • May show diffuse scarring, traction bronchiectasis, or honeycombing patterns.
  • Includes a variety of radiological patterns depending on the underlying cause.
• Interstitial Fibrosis:
  • Specifically shows patterns involving the interstitial tissue, such as:
    • Reticular opacities.
    • Honeycombing.
    • Ground-glass opacities in the early stages.

Summary:

• Pulmonary fibrosis is a general term encompassing all lung scarring, whereas interstitial fibrosis specifically refers to scarring of the interstitial lung tissue.
• All interstitial fibrosis is pulmonary fibrosis, but not all pulmonary fibrosis is interstitial.

Pulmonary fibrosis is a chronic lung condition characterized by the
progressive scarring and thickening of the lung interstitium, leading
to stiff, less elastic lungs that impair normal breathing. This scarring
can result from a variety of causes, including autoimmune diseases
(like rheumatoid arthritis or scleroderma), environmental exposures
(such as asbestos, silica, or other inhaled toxins), chronic
infections, and certain medications. In many cases, the cause is
unknown, leading to the term idiopathic pulmonary fibrosis (IPF).
The pathogenesis involves ongoing injury to the alveoli, followed by
abnormal healing and excessive deposition of fibrous tissue, which
replaces normal lung architecture. Symptoms typically include
persistent dry cough, progressive shortness of breath, fatigue, and
reduced exercise tolerance. Diagnosis is based on a combination of
clinical evaluation, pulmonary function tests (PFTs) showing a
restrictive pattern, and imaging, particularly high-resolution CT
scans, which reveal reticular patterns, honeycombing, and traction
bronchiectasis.