Idiopathic Pulmonary Fibrosis is one of many lung diseases that leave scar or fibrosis in the lungs. Patients with IPF generally are older than 50 years of age and don’t have a connective tissue disease such as rheumatoid arthritis or lupus or other diseases associated with scarring in the lungs. The high resolution CT scans show lower lobe predominant peripherally located scar that has a characteristic appearance. Some patients will require a lung biopsy to arrive at the correct diagnosis.
We now know that immunosuppressive medications are not helpful in IPF. Without treatment, IPF is generally progressive and average survival is between two and three years. With the currently approved therapies (OFEV and Esbriet), survival is now better.
There are many other causes of scarring or fibrosis in the lungs. Each has a different prognosis and treatments vary. Here is a list of some of the more common lung diseases that cause fibrosis.
Non-Specific Interstitial Pneumonitis (NSIP)
This comes in two sub-types. Cellular has a better prognosis and generally responds to prednisone and other immunosuppressive medications. Patients who are diagnosed early enough generally have a good prognosis. Patients that present late in the course of their disease will respond less well to treatment and have a worse prognosis. The high resolution CT scan in NSIP has more ground glass opacities (haziness) and generally lacks honeycomb change (thick scar like areas at the periphery of the lungs). On lung biopsy there are no fibrotic foci and the distribution is more homogeneous.
Fibrotic NSIP behaves much more like IPF and has a prognosis between cellular NSIP and IPF. Immunosuppressive medications are still used but patients tend to respond less well.
Connective Tissue Associated Interstitial Lung Disease
Patients with scleroderma and rheumatoid arthritis may develop pulmonary fibrosis. In patients with scleroderma, recent studies have supported the use of mycophenolate (a potent immunosuppressive medication). In the studies, patients have improvement in their lung disease but some will still progress.
Patients with rheumatoid arthritis who develop pulmonary fibrosis often have a difficult and progressive course. Little good quality data is available but in my experience is the pulmonary fibrosis in the context of rheumatoid arthritis responds poorly to immunosuppressive medications. We often worry about the possibility of the rheumatoid arthritis medication methotrexate causing pulmonary fibrosis but this is often considered and rarely seen.
Radiation Therapy Induced Pulmonary Fibrosis
Patients treated with radiation therapy for cancer of the neck, chest, breast or lungs can develop acute and chronic complications. A late complication is pulmonary fibrosis. Unlike other types of pulmonary fibrosis this disease generally is limited to the area of the lung tissue that was exposed to the radiation therapy. The involved lung can become severely fibrotic but the remaining lung tissue remains normal.
This is an increasingly recognized cause of pulmonary fibrosis. Patients react to something in their environment such as mold or bird feathers and develop a progressive lung disease. Unlike IPF, this type of lung disease usually starts in the top of the lungs and the pulmonary function pattern and chest imaging are quite different from IPF. The diagnosis is suggested by tiny nodules and air trapping on the high resolution CT scan. Bronchoscopy may be useful. When identified early and the offending agent is removed, the prognosis is good. However, many patients come to attention late and it is difficult to treat advanced disease. Prednisone is often used.
This is a complicated disease that can involve lungs but also any other part of the body. We don’t understand the cause. In some patients the lung disease is progressive and scarring or fibrosis can develop. The scarring is usually worst in the tops of the lungs, though in some patients it may look more like IPF. Other features are usually present that suggest sarcoid.
This is a rare lung disease generally seen in smokers. It preferentially involves the tops of the lungs and usually has tiny nodules. The most important early intervention is to stop smoking. We have few studies that direct our treatment. Prednisone is often tried.
Desquamative Interstitial Pneumonitis (DIP)
This is another lung disease of smokers. Patients have cough and shortness of breath. The high resolution CT scan shows wide spread ground glass (haziness). Patients must stop smoking. Prednisone is often used though high quality studies are lacking.
Medication Induced Pulmonary Fibrosis
Certain medications can lead to scarring in the lungs. Although many medications may have a few reports of fibrosis in the lungs associated with their use, there are a few medications that are more likely to cause lung scarring. A few of these medications include bleomycin a cancer treatment), nitrofurantoin (an antibiotic used for patients struggling with chronic bladder infections) and amiodarone (a heart medication).