What Is Interstitial Lung Disease?
The interstitium is a lace-like network of tissue that goes throughout both lungs. It supports your lungs' tiny air sacs, called alveoli. Normally, the interstitium is so thin that it doesn’t show up on X-rays or CT scans.
Types of Interstitial Lung Disease
All forms of interstitial lung disease cause the interstitium to thicken. This can happen from inflammation, scarring, or a buildup of fluid. Some forms of ILD last a short time (acute); others are long-term (chronic) and don’t go away.
Some types of interstitial lung disease include:
- Interstitial pneumonia. Bacteria, viruses, or fungi can infect the interstitium. A bacteria called Mycoplasma pneumoniae is the most common cause.
- Idiopathic pulmonary fibrosis. This makes scar tissue grow in the interstitium. Experts don’t know what causes it.
- Nonspecific interstitial pneumonitis. This is an interstitial lung disease that often affects people with autoimmune conditions such as rheumatoid arthritis or scleroderma.
- Hypersensitivity pneumonitis. This happens when dust, mold, or other things that you breathe irritate your lungs over a long time.
- Cryptogenic organizing pneumonia (COP). COP is a pneumonia-like interstitial lung disease without an infection. You might hear your doctor call this bronchiolitis obliterans with organizing pneumonia (BOOP).
- Acute interstitial pneumonitis. This is a sudden, severe interstitial lung disease. People who have it often need to be connected to a machine called a ventilator that breathes for them.
- Desquamative interstitial pneumonitis. This is an interstitial lung disease that partly results from smoking.
- Sarcoidosis. This causes interstitial lung disease along with swollen lymph nodes. It can also affect your heart, skin, nerves, and eyes.
- Asbestosis. This is an interstitial lung disease caused by breathing asbestos, a fiber used in building materials.
Interstitial Lung Disease Symptoms
The most common symptom of all forms of interstitial lung disease is shortness of breath. Almost everyone with ILD will have breathlessness, which can get worse over time.
Other symptoms of interstitial lung disease include:
- Cough, which is usually dry and doesn’t bring up mucus.
- Weight loss, most often in people with COP or BOOP.
With most forms of ILD, shortness of breath develops slowly (over months). If you have interstitial pneumonia or acute interstitial pneumonitis, your symptoms will come on quickly (in hours or days).
Interstitial Lung Disease Causes and Risks
The cause of most interstitial lung disease is unknown.
Bacteria, viruses, and fungi can cause interstitial pneumonia. You can also get ILD if you regularly breathe in things that can bother your lungs. These include:
- Bird proteins (such as from exotic birds, chickens, or pigeons)
- Coal dust or various other metal dusts from working in mining
- Grain dust from farming
- Silica dust
It’s rare, but certain drugs can cause ILD:
- Some antibiotics, like nitrofurantoin
- Some anti-inflammatory drugs, like rituximab
- Chemotherapy drugs like bleomycin
- Heart medications such as amiodarone
Anyone can get interstitial lung disease, but some things can put you at higher risk:
Interstitial Lung Disease Diagnosis
People with interstitial lung disease usually go to the doctor because of shortness of breath or a cough. Your doctor will probably use imaging tests of your lungs to find out the problem.
Chest X-ray. A simple chest X-ray is the first test for most people with a breathing problem. Chest X-rays in people with interstitial lung disease may show fine lines in the lungs.
CT scan. A CT scan takes multiple X-rays of the chest, and a computer creates detailed images of the lungs and surrounding structures. These tests can usually find interstitial lung disease.
High-resolution CT scan. If your doctor thinks you have an interstitial lung disease, certain CT scan settings can get better-quality images of your interstitium. This can help your doctor diagnose you.
Lung function test. You sit in a sealed plastic booth and breathe through a tube to measure your total lung capacity, which might be reduced if you have ILD. You may also be less able to transfer oxygen from your lungs into your blood.
Lung biopsy. Looking at lung tissue under a microscope is often the only way for a doctor to know which type of interstitial lung disease you have. Lung tissue is collected in a procedure called a lung biopsy, which can be done several ways:
- Bronchoscopy. Your doctor will run a tube called an endoscope through your mouth or nose and into your airways. Tiny tools on the endoscope can take a sample of lung tissue.
- Video-assisted thoracoscopic surgery (VATS). Your doctor will make small cuts to insert tools that take samples from multiple areas of lung tissue.
- Open lung biopsy (thoracotomy). In some cases, you might need traditional surgery with a large incision in the chest to get a lung biopsy.
Treatments for Interstitial Lung Disease
The treatment you get depends on the type of ILD you have and its cause.
Antibiotics. These treat most interstitial pneumonias. Pneumonias caused by a virus usually get better on their own. Pneumonias caused by a fungus are rare but are treated with antifungal drugs.
Corticosteroids. In some forms of interstitial lung disease, inflammation in your lungs causes damage and scarring. Corticosteroids cause your immune system’s activity to slow. This lessens the amount of inflammation in your lungs and the rest of your body.
Inhaled oxygen. If you have low oxygen levels because of interstitial lung disease, inhaled oxygen may help your symptoms. Regular use of oxygen might also protect your heart from damage caused by low oxygen levels.
Lung transplant. In advanced interstitial lung disease that has severely impaired you, you may need a lung transplant. Most people who have a lung transplant for interstitial lung disease make large gains in their quality of life and their ability to exercise.
Azathioprine (Imuran). This drug also slows down the immune system. It’s not shown to improve interstitial lung disease, but some studies suggest it might help.
N-acetylcysteine (Mucomyst). This potent antioxidant may slow the decline of lung function in some forms of interstitial lung disease. You’ll take it in combination with other treatments.
Other drugs are considered controversial for interstitial lung disease treatment, including:
These medicines affect the way your immune system works. If your doctor thinks you need one, they’ll keep a close watch on you while you’re taking it. These medications can have serious side effects.
Interstitial Lung Disease Complications
The complications of severe interstitial lung disease can be life threatening:
- High blood pressure in your lungs, known as pulmonary hypertension
- Respiratory failure
- Right-sided heart failure, known as cor pulmonale