Interstitial lung disease (ILD) refers to a group of lung diseases affecting the tissue and space around the air sacs of the lungs (the interstitium). It concerns alveolar epithelium, pulmonary capillary endothelium, basement membrane, perivascular and perilymphatic tissues.
Interstitial lung diseases include:
- Hypersensitivity Pneumonitis
- Idiopathic Pulmonary Fibrosis
Hypersensitivity pneumonitis (HP) is an interstitial lung disease caused by repeated inhalation of certain fungal, bacterial, animal protein or reactive chemical particles, called antigens. While most people who breathe in these antigens don’t develop problems, in some people, the body’s immune reaction to these particles causes inflammation of the lung. In some cases, parts of the lungs may become scarred.
HP should not be confused with the more common types of allergies, which are caused by small amounts of proteins in the environment such as dust mites, cat dander, pollen and grass. Having seasonal or environmental allergies has nothing to do with having or developing HP.
It’s not known why a minority of people exposed to these antigens develop HP. Their genetics and environment may interact to make them more susceptible to the disease.
Hypersensitivity pneumonitis (HP) is subdivided into two forms: acute and chronic. Symptoms differ for each form.
- The acute form of HP occurs after heavy, often short-term exposure to the antigen. Symptoms appear relatively suddenly and include fever, chills, fatigue, breathlessness, chest tightness and cough. If the person is removed from the antigen exposure, the symptoms usually resolve over 24 to 48 hours. Recovery is often complete.
- The chronic form of HP is thought to occur due to longer term, low-level exposure to the antigen, and it often causes more subtle symptoms. Patients with chronic HP often describe chronic symptoms, such as shortness of breath or cough, that have gotten worse. Symptoms may worsen at work, at home or wherever the patient is being exposed to the antigen, but most often, patients with chronic HP haven’t had acute episodes.
The best treatment is to avoid the provoking allergen, as chronic exposure can cause permanent damage. Corticosteroids such as Prednisolone may help to control symptoms but may produce side-effects.
In addition to medications and removal of the antigen, pulmonary rehabilitation — a structured exercise and educational program designed for patients with chronic lung disease — is an important and effective treatment for patients with chronic HP.
Lung transplant may be an effective treatment option for some patients.
Idiopathic Pulmonary Fibrosis
Idiopathic pulmonary fibrosis, or IPF, is a condition that causes progressive scarring of the lungs. Fibrous scar tissue builds up in the lungs over time, affecting their ability to provide the body with enough oxygen.
IPF affects more than 100,000 people in North America, with 30,000 to 40,000 new cases diagnosed each year. Typically the disease is found in people between the ages of 50 and 70 and affects men more frequently than women. Most patients are former smokers. There are no proven risk factors for IPF, but a minority of patients does have a family history of lung scarring.
The cause of the condition is unknown.
Symptoms and signs of IPF often appear gradually and include:
- Shortness of breath, particularly during or after physical activity
- Chronic, dry hacking cough
- Crackles in the lungs heard through a stethoscope
- Rounding of the fingernails, a condition called clubbing
Symptoms of IPF may mimic those of other diseases that cause lung scarring, so diagnosing IPF often involves ruling out other conditions. Several visits with your doctor may be needed to finalize your diagnosis and treatment approach.
There is no cure for IPF and currently no satisfactory treatment exists. Medical studies suggest a potential role for several therapies, but further study is needed.
Pulmonary rehabilitation — a structured exercise and educational program designed for patients with chronic lung disease — is important for patients with IPF. Lung transplant may be an effective treatment option for some patients.
Sarcoidosis is a disorder that causes inflamed tissue called nodules or granulomas to develop in the body’s organs, most often the lungs. It can also affect the skin, eyes, nose, muscles, heart, liver, spleen, bowel, kidney, testes, nerves, lymph nodes and brain. Nodules in the lungs can lead to narrowing of the airways and inflammation, also called fibrosis, of lung tissue.
Sarcoidosis affects people of all ages, races and gender, though it most commonly occurs in people between 20 to 40 years old. Children are rarely diagnosed with the disease. In very few cases, more than one family member is affected. African Americans are three to four times more likely to have sarcoidosis and may have a more severe form of the disease than people of European descent.
The exact cause of sarcoidosis is not known.
Symptoms of sarcoidosis may differ in each person and depends on the organs affected. Frequently, the condition causes mild symptoms and resolves on its own without treatment. In approximately half of all patients, sarcoidosis is detected on a routine chest X-ray before any symptoms develop.
The most common symptoms of sarcoidosis involving the lungs include:
- Shortness of breath
- Chest pain, which is usually a vague tightness of the chest, but can occasionally be severe and similar to the pain of a heart attack
- Weight loss
There is no specific treatment to cure the condition at this time. Fortunately, between 30 and 70% of patients do not require therapy because the nodules gradually resolve on their own and leave behind few, if any, signs of inflammation or other complications.
However, treatment is necessary in some cases. Medications are available that effectively suppress symptoms and help reduce lung inflammation, the impact of nodules and prevent the development of lung fibrosis. These include:
- Cyclophosphamide and Azathioprine
- Antimalarial Medications (Hydroxychloroquine)
A number of other medications are currently being investigated for the treatment of sarcoidosis