Pulmonary Fibrosis: Causes, Diagnosis & Treatment
Summary: Pulmonary fibrosis is a progressive lung disease marked by scarring and stiffening of lung tissues, making it hard to breathe. This article covers the causes, symptoms, diagnosis (including HRCT and PFTs), treatment options (like antifibrotics and lung transplants), and includes helpful mnemonics and a real-life clinical case to make understanding easier.
Definition
Pulmonary fibrosis is a group of lung diseases causing progressive fibrosis of the lung parenchyma, leading to restrictive lung disease and respiratory compromise. It is associated with various etiologies, including idiopathic pulmonary fibrosis (IPF), connective tissue disorders, and environmental exposures.
Pathology
- Histopathology: Characterised by
- Excessive extracellular matrix deposition
- Fibroblast proliferation
- Honeycombing
- Idiopathic Pulmonary Fibrosis (IPF): The most common form, marked by the usual interstitial pneumonia (UIP) pattern on high-resolution CT.
- Secondary Pulmonary Fibrosis: Can result from
- Connective tissue diseases (scleroderma, rheumatoid arthritis)
- Chronic hypersensitivity pneumonitis
- Drug-induced lung injury
Types of Pulmonary Fibrosis
Pulmonary fibrosis isn’t a single disease, it’s an umbrella term for a group of conditions that cause progressive scarring of the lungs. Each type has a different trigger, from unknown causes to autoimmune diseases or environmental exposures.
Below are the major types of pulmonary fibrosis:
- Idiopathic Pulmonary Fibrosis (IPF)
- Connective Tissue Disease-Associated Pulmonary Fibrosis
- Hypersensitivity Pneumonitis
- Pneumoconiosis (Asbestosis, Silicosis, Coal Worker’s Pneumoconiosis)
- Radiation-Induced Pulmonary Fibrosis
- Drug-Induced Pulmonary Fibrosis (Amiodarone, Bleomycin, Methotrexate)
What Are the Common Symptoms of Pulmonary Fibrosis?
Pulmonary fibrosis symptoms often develop gradually and worsen over time. They typically reflect reduced lung capacity and oxygenation.
Key signs and symptoms include:
Progressive exertional dyspnea (shortness of breath during activity)
Chronic dry cough that doesn’t go away
Clubbing of fingers (rounded, enlarged fingertips)
Bibasilar inspiratory crackles (often described as “Velcro crackles” heard at the lung bases)
Fatigue and weight loss in more advanced stages
How Is Pulmonary Fibrosis Diagnosed?
Diagnosing pulmonary fibrosis involves a combination of blood tests, imaging, and lung function assessments to confirm scarring and rule out other causes.
Laboratory Tests?
Autoimmune screening: Tests like ANA, RF, and Anti-Scl70 help detect underlying connective tissue diseases.
Fibrosis biomarkers: Elevated KL-6, surfactant protein-D (SP-D), and LDH levels can indicate ongoing lung damage.
Imaging Studies
Chest X-ray: Shows reticular opacities (net-like patterns) and reduced lung volume.
High-Resolution CT (HRCT): The gold standard. Identifies honeycombing, reticulation, and subpleural fibrosis, especially in UIP patterns typical of Idiopathic Pulmonary Fibrosis (IPF).
Pulmonary Function Tests (PFTs)
Shows a restrictive pattern: Decreased FVC (Forced Vital Capacity), TLC (Total Lung Capacity), and DLCO (Diffusing capacity of the lungs for carbon monoxide).
FEV1/FVC ratio: Normal or even slightly increased, helping differentiate it from obstructive diseases like COPD.
What Conditions Can Mimic Pulmonary Fibrosis?
Several diseases can present with similar symptoms and imaging findings. A thorough differential diagnosis helps ensure accurate treatment.
Key Conditions to Rule Out:
Chronic Obstructive Pulmonary Disease (COPD)
Typically shows an obstructive pattern on PFTs
Strongly associated with a history of smoking
Sarcoidosis
Characterised by hilar lymphadenopathy and non-caseating granulomas on biopsy
May have systemic involvement (e.g., skin, eyes, joints)
Presents with Kerley B lines and cardiomegaly on chest X-ray
Often includes symptoms like leg swelling and orthopnea
Bronchiolitis Obliterans
A rare obstructive lung disease
Often occurs post-infection, after transplant, or due to inhalation injury
Treatment Options for Pulmonary Fibrosis
Managing pulmonary fibrosis involves slowing disease progression, relieving symptoms, and improving quality of life. Treatment depends on the type and severity of the disease.
Pharmacologic Therapy
Antifibrotic Agents (for Idiopathic Pulmonary Fibrosis)
Pirfenidone: 801 mg orally, three times daily
Nintedanib: 150 mg orally, twice daily
These drugs help slow down lung scarring and preserve lung function.
Immunosuppressive Therapy (for autoimmune-related fibrosis)
Mycophenolate mofetil: 1–3 g/day
Azathioprine: 1–2 mg/kg/day
These are used when fibrosis is linked to connective tissue diseases.
Supportive Therapy
Oxygen therapy: For patients with hypoxemia (low oxygen levels)
Pulmonary rehabilitation: Improves breathing efficiency, stamina, and overall well-being
Surgical Interventions
Lung Transplantation
A life-saving option for patients with end-stage pulmonary fibrosis
Lung Volume Reduction Surgery (LVRS)
Considered in select cases with localized fibrotic damage
Pulmonary Fibrosis: Key Statistics
Understanding the numbers helps highlight the seriousness of pulmonary fibrosis and the need for early diagnosis and management.
Global prevalence: Affects approximately 13–20 people per 100,000 individuals
5-year survival rate: Estimated at 20% to 40%, depending on the type and stage of the disease
Clinical Case of Idiopathic Pulmonary Fibrosis (IPF)
Let’s look at a real example that shows how pulmonary fibrosis is diagnosed and managed.
Patient Overview
A 65-year-old man visited the doctor with complaints of increasing breathlessness, a persistent dry cough, and feeling tired most of the time.
What Tests Showed
A High-Resolution CT (HRCT) scan revealed typical signs of lung damage, honeycombing and scarring in the lower parts of the lungs.
Lung function tests showed a restrictive pattern, meaning the lungs couldn’t expand properly. His DLCO (ability to transfer oxygen) was also low.
Diagnosis
Doctors diagnosed him with Idiopathic Pulmonary Fibrosis (IPF)—a progressive lung condition with no known cause.
Treatment Plan and Progress
He was started on Pirfenidone (801 mg, three times a day)—a medicine that helps slow lung scarring.
He also began pulmonary rehab and was given home oxygen therapy to help with breathing.
After six months, his condition was stable, and his symptoms were better controlled
Mnemonics for Pulmonary Fibrosis
- “FIBROSIS” for Symptoms
- Fatigue
- Inspiratory crackles
- Breathlessness
- Restrictive pattern on PFTs
- Oxygen desaturation
- Scarring on HRCT
- Immunological causes (CTD, Sarcoidosis)
- Smoking-related (some forms)
2. Causes – “SAND DUST”
- Sarcoidosis
- Asbestosis
- Nitrofurantoin (drug-induced)
- Drugs (Amiodarone, Bleomycin)
- Dermatomyositis
- UIP (Usual Interstitial Pneumonia)
- Scleroderma
- TB (Post-infectious fibrosis)
Dr Darshit patel, MD
I am an MBBS graduate and a dedicated medical writer with a strong passion for deep research and psychology. I enjoy breaking down complex medical topics into engaging, easy-to-understand content, aiming to educate and inspire readers by exploring the fascinating connection between health, science, and the human mind.
