Interstitial lung disease (ILD) describes a large group of disorders characterized by progressive scarring of the lung tissue between and supporting the air sacs. The scarring associated with interstitial lung disease may cause progressive lung stiffness, eventually affecting your ability to breathe and get enough oxygen into your bloodstream.
There are known causes like certain drugs (nitrofurantoin, bleomycin, sulfonamides, gold, amiodarone, methotrexate), radiation treatment to the chest, some occupations (exposure to asbestos, silica, coal dust), exposure to pigeon droppings, autoimmune conditions such as rheumatoid arthritis, scleroderma and hence a careful history of occupational and environmental exposures is essential. Usually no cause is obvious and the ILD is then labelled Idiopathic Interstitial Pneumonia which includes Idiopathic Pulmonary Fibrosis (IPF) which has a worse prognosis and Non Specific Interstitial Pneumonia (NSIP) which carries a better prognosis.
The primary signs and symptoms of ILD include dry cough and shortness of breath at rest or with exertion. At first shortness of breath may not be severe and is only noticed with exercise, climbing stairs and other activities. Over time it can occur with less strenuous activities such as bathing or dressing.
A good quality CT scan of the chest (HRCT) is crucial in determining the type of ILD. Spirometry and diffusion capacity give an idea of the extent of fibrosis and the disability it has produced. A six minute walk test is also a good way of assessing the patients functional status and is of prognostic value. A bronchoscopy and trans-bronchial biopsy and, on occasion, an open lung biopsy may be needed to establish the type of ILD.
Treatment depends on the cause of the disease. Medicines that suppress the immune system and decrease lung inflammation such as steroids are prescribes for certain types of ILDs. For IPF, pirfenidone is at present available in India and nintedanib is under research. Other supportive treatment for ILD includes oxygen therapy, pulmonary rehabilitation, vaccination and lung transplantation.