Interstitial Lung Disease (ILD)

🫁 Interstitial Lung Disease (ILD)

Interstitial Lung Disease (ILD) refers to a group of more than 300 lung conditions that cause inflammation and scarring (fibrosis) of the lung tissue. While most ILDs are rare, the more common types include:

• Idiopathic Pulmonary Fibrosis (IPF)

• Sarcoidosis

• Non-Specific Interstitial Pneumonia (NSIP)

• Extrinsic Allergic Alveolitis (Hypersensitivity Pneumonitis)

• ILD associated with Connective Tissue Disease

• Pneumoconiosis

• Drug-induced Interstitial Lung Disease

Some ILDs—especially sarcoidosis—may also affect other organs in the body.

📊 Prevalence & Classification

Research on ILD prevalence is complex, as many cases lack a specific diagnosis. However, it is estimated that Idiopathic Pulmonary Fibrosis (IPF) and Sarcoidosis together account for around 50% of ILD cases.

ILDs are typically classified into:

• Diseases with a known cause

• Diseases with unknown origin

⚠️ Symptoms of Interstitial Lung Disease

Symptoms usually develop gradually and may include:

• Shortness of breath (especially during exertion)

• Dry, persistent cough

• Fatigue and decreased exercise tolerance

• Cyanosis (blue/purple discoloration of lips, fingers, toes)

• Clubbing (swelling of fingers)

🧬 Causes of ILD

Only about 1 in 3 ILD cases has a known cause. The disease often results from a combination of genetics and environmental factors. Key causes include:

🌫️ Environmental or Occupational Exposure:

• Pneumoconiosis: Due to inhalation of harmful particles like:

  • Silica dust (Silicosis)

  • Coal dust (Coal Worker’s Pneumoconiosis)

  • Asbestos (Asbestosis)

🐦 Organic Allergens:

• Extrinsic Allergic Alveolitis: Triggered by inhaled organic agents like:

  • Mouldy hay (Farmer’s Lung)

  • Bird droppings/feathers (Bird Fancier’s Lung)

💊 Drug-Induced ILD:

Certain medications can lead to ILD, including:

• Amiodarone – for arrhythmia

• Bleomycin – a chemotherapy drug

• Methotrexate – used for arthritis

• Nitrofurantoin – for UTIs

🔐 Prevention of ILD

Prevention is possible only when the cause is known. The best method is to avoid exposure to known environmental or occupational risk factors.

In the future, experts hope to identify genetic markers to predict ILD risk and tailor prevention strategies individually.

🩺 Diagnostic Tests & Investigations

Essential ILD investigations include:

• Chest X-rays and High-Resolution CT (HRCT) Scans: Reveal patterns like:

  • Fine nodules

  • Net-like haziness

  • ‘Honeycombing’ in advanced fibrosis

• Lung Function Tests:

  • Spirometry

  • Diffusion Capacity Testing

  • 6-Minute Walk Test (6MWT)

  • Oxygen Saturation

🧪 Lung Biopsy:

Sometimes required for accurate diagnosis, though less common now due to advanced imaging techniques.

💊 ILD Treatment Options

Treatment depends on the ILD type and disease progression:

• Anti-fibrotic drugs and anti-inflammatory medications are commonly used.

  • More effective in sarcoidosis, hypersensitivity pneumonitis, and rare ILDs.

  • Limited effect in idiopathic pulmonary fibrosis (IPF).

• Oxygen therapy and pulmonary rehabilitation may be needed in advanced stages.

• Lung transplantation is considered when ILD progresses despite treatment.

📈 ILD Prognosis & Survival

Survival rates vary by ILD type:

• Idiopathic Pulmonary Fibrosis: ~20% survive beyond 5 years post-diagnosis

• Sarcoidosis / Hypersensitivity Pneumonitis: 80–100% 5-year survival