Diagnosis
While ILD is fairly uncommon in the general population, about 15% of the patients seen by pulmonologists (lung specialists) are ultimately diagnosed with ILD. Therefore, if ILD is suspected or if other diagnoses seem inappropriate, it is reasonable for patients to consult with someone who has experience in diagnosing and treating these uncommon diseases.
Diagnosis of ILD begins with a thorough patient history to review past symptoms and disease course. There will be an exhaustive discussion about possible exposures and genetic predispositions. This discussion can be made more fruitful if the patient considers possible exposures in advance of the visit. Also, any previous chest X-rays or CT scans could prove invaluable to the diagnosing physician.
A physical examination will be performed, mostly to rule out other causes of lung disease. Based on clinical judgment, any number of the following imaging studies and procedures are performed, usually starting with the least invasive and moving to more invasive tests until the diagnosis is definitively made. Chest X-ray, high resolution CT scan, pulmonary function tests, exercise tolerance tests, bronchoscopy, bronchoalveolar lavage (BAL), and video-assisted thoracoscopic surgery (VATS) are the main diagnostic modalities.
Bronchoscopy is a procedure in which a thin, flexible tube with an internal camera is advanced into the lungs to look for pathological changes. A small biopsy with instruments in the tip of the bronchoscope may be taken.
Bronchoalveolar lavage may be performed with bronchoscopy. In this procedure, physiological saline is used to flush cells out of the lungs which are retrieved and sent to a pathologist for analysis. The cells obtained in a BAL are not used to diagnose ILD as much as they are to check for lung cancer and related lung illnesses. If these tests fail to confirm a diagnosis, a VATS procedure may be needed to obtain a lung biopsy. During VATS, an endoscope (thorascope) is advanced through a small incision in the chest wall and a diseased piece of lung is taken for analysis.
There has been a great deal of optimism regarding several blood tests for ILD. Unfortunately serum biomarkers are not yet ready for routine use if diagnosis; however, some blood tests may be used judiciously in specific cases. In the near term, some markers may be more useful for following disease progression and response to treatment rather than providing diagnostic information.
Treatment
Since the major problems associated with ILD are caused by an immune system reaction, treatment is aimed at curbing the immune response and inflammation. Therefore immunosuppressants and anti-inflammatory drugs are the mainstay of treatment. Corticosteroids like prednisone for outpatient care and methylprednisolone intravenously for acute, inpatient flare-ups are most commonly used. Unfortunately, long term use of corticosteroids is associated with a number of side effects, many of which are permanent. Colchicine, a treatment commonly used in gouty arthritis, has been helpful in select patients though again, side effects limit its use.
More aggressive pharmacological therapy includes drugs like cyclophosphamide and azathioprine. While these may prevent patients from incurring the effects of long term steroid use, they have their own side effect profiles. Clinical trials of newer cytokine agents and disease-modifying drugs in ILD have been disappointing.
In select patients, generally with advanced disease, lung transplantation may be an option. Lung transplantation is still technically challenging and long term survival is lower than it is for other organ transplants. Nevertheless, three quarters of patients with ILD survive to one year after single lung transplantation and one quarter of patients live at least ten years.
Unfortunately the management of ILD can be frustrating for physicians and deeply depressing for patients and caregivers. Because the disease worsens with time and treatment options are quite limited, patients are left with few choices. Quitting smoking is essential in anyone with ILD. Pulmonary physical therapy can help reduce symptoms and improve lung capacity. Supplemental oxygen can also make living with ILD more comfortable. Patient and family support groups provide patients an extended support system, additional resources, and improved quality of life.
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